Chair

Abstract

To realize a chair capable of keeping stability even when a user stands up while bracing a hand against the chair.SOLUTION: A chair (1) includes: a cylindrical first member (17) having an opening in a vertical direction; and a second member (16) to be inserted to the opening of the first member (17) and abutted to an inner side surface of the first member (17) when a reception member (13) receives force equal to or more than a first predetermined value, thereby to suppress rotation of the reception member (13) with respect to a leg part (12).SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a chair. [Background technology]

[0002] Conventionally, chairs equipped with a locking mechanism for fixing the chair body to the floor surface are known. For example, Patent Document 1 discloses a chair equipped with a fixing mechanism having a stopper for pressing the floor surface, a pressing means for projecting the stopper toward the floor surface, and an operating means for operating the pressing means, at the legs of the chair body with casters. In the chair described in Patent Document 1, the stopper operates to press the floor surface by operating the operating means, thereby fixing the chair body with casters to the floor surface. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2000-135134 A (published May 16, 2000) Summary of the Invention [Problem to be solved by the invention]

[0004] However, the chair described in Patent Document 1 has room for improvement in terms of stability when used by a user who has difficulty in using his / her knees or who has reduced muscle strength in the lower body.

[0005] People who have difficulty using their knees or who have weakened muscles in their lower body tend to use the chair as a walking stick to stand up. In this case, if the chair has a rotation mechanism that rotates the seat relative to the legs, the chair described in Patent Document 1 will rotate and move the part where the user is holding the seat when trying to stand up, making the chair unstable. This can cause the user to fall.

[0006] One aspect of the present invention aims to provide a chair that allows a person who has difficulty in using their knees or who has reduced muscle strength in the lower body to maintain stability when standing up by placing their hands on the chair. [Means for solving the problem]

[0007] In order to solve the above problems, a chair according to one embodiment of the present invention comprises a seat, legs supporting the seat, a receiving member that receives force applied downward by a user, a rotation mechanism that rotates the receiving member relative to the legs, and a restraining mechanism that prevents rotation of the receiving member by the rotation mechanism, wherein the restraining mechanism comprises a cylindrical first member having an opening in the vertical direction, and a second member that is inserted into the opening of the first member and abuts against the inner surface of the first member when the receiving member receives a force equal to or greater than a first predetermined value, thereby preventing rotation of the receiving member relative to the legs.

[0008] According to the above configuration, when the receiving member receives a force equal to or greater than the first predetermined value, the rotation of the receiving member is prevented by the prevention mechanism. By applying a force to the receiving member, the rotation of the receiving member relative to the legs can be prevented, so that the user can be prevented from falling over when standing up by putting their hands on the chair.

[0009] In addition, according to the above configuration, the restraining mechanism is provided on the chair. When a chair support mechanism having a restraining mechanism is attached to the chair body of a commercially available chair, the components of the chair support mechanism become large, and the chair becomes too heavy after attachment. By providing the restraining mechanism on the chair, the chair can be made lighter than when the chair support mechanism is attached to the chair body, and the chair can be made easier to handle.

[0010] Furthermore, the restraining mechanism is composed of a cylindrical first member and a second member inscribed in the first member. In the case of such a structure, by providing a cylindrical first member coaxial with the rotation axis, it is possible to provide a restraining mechanism that is compact and unnoticeable in design while ensuring a sufficient contact area between the first member and the second member required for rotation restraint.

[0011] The chair further includes a seat rotation limiting member that limits rotation of the seat relative to the receiving member when rotation of the receiving member is prevented by the preventing mechanism.

[0012] According to the above-mentioned configuration, when the rotation of the receiving member is restrained by the restraining mechanism, the rotation of the seat section relative to the receiving member is restrained. By applying a force to the receiving member, the user can limit the rotation of the receiving member and the seat section together, so that the user can more reliably prevent falling over when standing up by putting his / her hands on the chair.

[0013] In the above chair, one of the first member and the second member has internal teeth and the other has external teeth, and the restraining mechanism prevents rotation of the receiving member relative to the leg by causing the external teeth to abut against the internal teeth when the receiving member receives a force greater than the first predetermined value.

[0014] According to the above configuration, by abutting the external teeth against the internal teeth, it is possible to reliably prevent the reception member from rotating relative to the leg portion.

[0015] In the above chair, the second member has a viscoelastic body, and the restraining mechanism prevents rotation of the seat relative to the legs by elastically deforming the viscoelastic body in response to the force received by the receiving member and the viscoelastic body abutting the inner surface of the first member.

[0016] According to the above configuration, the restraining mechanism restrains the rotation of the receiving member by abutting the viscoelastic body of the second member against the inner surface of the cylindrical first member having an opening in the vertical direction. When using friction to restrain rotation relative to the legs, if the abutting area is secured in a two-dimensional manner, the chair itself becomes large. By abutting the inner surface of the cylindrical first member having an opening in the vertical direction against the second member and securing the abutting area three-dimensionally, the chair can be made smaller.

[0017] In the above chair, the legs are movable horizontally relative to the floor surface, and the restraining mechanism further restrains horizontal movement of the legs when the receiving member receives a force greater than or equal to the first predetermined value.

[0018] According to the above configuration, the restraining mechanism further restrains horizontal movement of the legs, thereby preventing the user from falling when standing up by putting his / her hands on the chair.

[0019] In the above chair, the restraining mechanism further has a stopper shaft, one of the first member and the second member has a first biasing member that biases the stopper shaft toward the floor surface, and the other has a second biasing member that biases the stopper shaft in a direction away from the floor surface, and when the receiving member receives a force equal to or greater than the first predetermined value, the stopper shaft is pressed against the floor surface by the combined force of the biasing force of the first biasing member and the biasing force of the second biasing member, thereby restraining the horizontal movement of the leg, and when the receiving member receives a force less than a second predetermined value that is equal to or less than the first predetermined value, the stopper shaft is moved away from the floor surface by the combined force of the biasing force of the first biasing member and the biasing force of the second biasing member.

[0020] According to the above configuration, by having the first and second biasing members, when the user releases the chair, the rotation of the receiving member relative to the legs can be automatically restored from the inhibited state.

[0021] In the above chair, the restraining mechanism causes either the first member or the second member to move up and down in response to a force received by the receiving member, and the restraining mechanism has a locking member that is arranged on the leg and is capable of transitioning between a first state that allows the leg to move horizontally and a second state that prevents the leg from moving horizontally, and a connecting member that links the locking member to the movement of one of the first member and the second member that moves up and down in response to the force received by the receiving member, and when the receiving member receives a force equal to or greater than the first predetermined value, the locking member transitions from the first state to the second state.

[0022] According to the above configuration, when the restraining mechanism restrains the rotation of the receiving member relative to the leg, the horizontal movement of the leg can be restrained. Effect of the Invention

[0023] According to one aspect of the present invention, it is possible to realize a chair that can maintain stability even when a person who has difficulty using their knees or who has weakened muscles in the lower body stands up while placing their hands on the chair. [Brief description of the drawings]

[0024] [Figure 1] FIG. 1 is a front view showing a schematic configuration of a chair according to a first embodiment of the present invention. [Diagram 2] 1 is a diagram showing a schematic configuration of a restraining mechanism in a chair according to a first embodiment of the present invention. [Diagram 3] FIG. 3 is a schematic view showing a cross section AA of FIG. 2. [Figure 4] 3A and 3B are diagrams showing a seat rotation limiting member in the chair according to the first embodiment of the present invention. [Diagram 5] FIG. 11 is a diagram showing a schematic configuration of a restraining mechanism in a chair according to a second embodiment of the present invention. [Figure 6] FIG. 11 is a diagram showing a schematic configuration of a restraining mechanism in a chair according to a third embodiment of the present invention. [Figure 7] FIG. 11 is a diagram showing a schematic configuration of a restraining mechanism in a chair according to a fourth embodiment of the present invention. [Figure 8] 1A and 1B are diagrams showing the schematic configuration of a suppression mechanism formed using an oil-free bushing. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] Hereinafter, an embodiment according to one aspect of the present invention (hereinafter also referred to as "the present embodiment") will be described with reference to the drawings. Note that the same or corresponding parts in the drawings are given the same reference numerals and their description will not be repeated. However, the present embodiment described below is merely an example of the present invention in every respect. It goes without saying that various improvements and modifications can be made without departing from the scope of the present invention. In other words, in implementing the present invention, a specific configuration according to the embodiment may be appropriately adopted.

[0026] The drawings also show three-dimensional coordinates of the XYZ system, with the XY plane defining the horizontal plane and the Z axis defining the vertical direction (the negative direction of the Z axis is the direction of gravity). In the following explanation, the front direction of the chair (positive Y direction in FIG. 1) is referred to as the "forward direction", and the back direction (negative Y direction in FIG. 1) is referred to as the "rearward direction". The right-hand direction of the chair body (negative X direction in FIG. 1) is referred to as the "rightward direction", and the left-hand direction of the chair body (positive X direction in FIG. 1) is referred to as the "leftward direction". The vertical upward direction (positive Z direction in FIG. 1) is referred to as the "upward direction", and the vertical downward direction (negative Z direction in FIG. 1) is referred to as the "downward direction". The leftward and rightward directions are referred to as the "left-right direction" when referring to them without distinction, and the upward and downward directions are referred to as the "upward and downward directions" when referring to them without distinction.

[0027] [Embodiment 1] §1 Examples of application Fig. 1 is a front view showing a schematic configuration of a chair according to this embodiment. As shown by reference numeral 1000 in Fig. 1, the chair 1 according to this embodiment includes a backrest 10, a seat portion 11, legs 12, an armrest 13, a support plate 14, an armrest fixing portion 15, a first support 16, a second support 17, and a stopper portion 18.

[0028] The legs 12 are located lower than the seat 11 and have a leg pillar 12A, casters 12B, and a seat rotation mechanism 12C. The leg pillar 12A of the legs 12 supports the seat 11 from below. The casters 12B abut against a floor surface F. The casters 12B enable the chair 1 to move horizontally on the floor surface F. The seat rotation mechanism 12C is connected to the leg pillar 12A and the seat 11. The seat 11 can rotate relative to the legs 12 around the seat rotation mechanism 12C.

[0029] Armrest 13 is an example of a receiving member. When a user who has difficulty putting strength into their knees or who has reduced muscle strength in their lower body (hereinafter referred to as "user") tries to stand up from chair 1, they place their hands on armrest 13A of armrest 13 and use chair 1 as a walking stick. When the user places their hands on armrest 13A, armrest 13 receives a downward force according to the user's weight.

[0030] The armrest 13 is fixed to the armrest fixing part 15. The armrest 13 and the armrest fixing part 15 are rotatable with respect to the leg part 12 around the seat rotation mechanism 12C. The receiving plate 14 is provided integrally with the seat part 11 so as to be rotatable with respect to the leg part 12 around the seat rotation mechanism 12C.

[0031] The armrest fixing part 15 has a boss 15A protruding upward. The boss 15A of the armrest fixing part 15 is inserted into a hole 14A of the receiving plate 14. Therefore, the armrest 13 and the armrest fixing part 15 can rotate integrally with the seat part 11 and the receiving plate 14 relative to the leg part 12 around the seat rotation mechanism 12C.

[0032] When the armrest 13 receives a downward force equal to or greater than a predetermined value, the armrest 13 and the armrest fixing portion 15 move downward together. Reference numeral 1000 in Fig. 1 indicates the state of the chair 1 when the armrest 13 is not receiving a downward force equal to or greater than a predetermined value. On the other hand, reference numeral 1001 in Fig. 1 indicates the state of the chair 1 when the armrest 13 receives a downward force corresponding to the weight of the user.

[0033] The first support 16 and the second support 17 are an example of a restraining mechanism. The first support 16 is an example of a second member of the restraining mechanism, and has a columnar shape extending in the vertical direction. The second support 17 is an example of a first member of the restraining mechanism, and has a tubular shape with an opening in the vertical direction. Here, the tubular shape is not limited to a cylinder, and includes any shape with openings at both ends. The first support 16 is fixed to the lower surface 15B of the armrest fixing part 15, and a part of it is inserted into the upper opening of the second support 17. A part of the side surface of the first support 16 has external teeth (described later). The second support 17 has internal teeth 17A arranged on a part of the inner side surface. As shown by the reference numeral 1000 in FIG. 1, when the armrest 13 does not receive a downward force of a predetermined value or more, the external teeth of the first support 16 do not abut against the internal teeth 17A of the second support 17. The first support 16 can rotate integrally with the armrest fixing part 15 relative to the leg part 12 around the seat rotation mechanism 12C. The second support 17 is fixed to the leg 12 and does not rotate relative to the leg 12 .

[0034] As shown by reference numeral 1001 in FIG. 1, when the armrest 13 receives a downward force of a predetermined value or more, the first support 16 moves downward together with the armrest fixing part 15. This movement causes the external teeth of the first support 16 to mesh with the internal teeth 17A of the second support 17. The state in which the external teeth on the side of the first support 16 mesh with the internal teeth 17A of the second support 17 is an example of a state in which the second member abuts against the inner side of the first member. When the external teeth of the first support 16 mesh with the internal teeth 17A of the second support 17, the rotation of the first support 16 relative to the leg 12 is suppressed. At this time, the rotation of the armrest fixing part 15 and the armrest 13, which are integrated with the first support 16, relative to the leg 12 is also suppressed. In addition, the rotation of the seat part 11 and the receiving plate 14, which are integrated with the armrest 13 and the armrest fixing part 15, relative to the leg 12 is also suppressed. Since the rotation of the armrest 13 relative to the leg 12 is inhibited, a user who is trying to stand up by putting his hands on the elbow rest 13A of the armrest 13 can be prevented from falling. Such an effect contributes to the achievement of Goal 3 of the Sustainable Development Goals (SDGs) advocated by the United Nations, "Good health and well-being for all." The chair 1 according to this embodiment is also made with a view to universal design, not just welfare. Therefore, by using the chair 1 according to this embodiment, people with weak legs and hips can work without distinction from able-bodied people, which allows them to feel the same "job satisfaction" as able-bodied people, and ultimately leads to "reducing inequalities." Such an effect contributes to the achievement of Goal 8, "Decent Work and Economic Growth," and Goal 10, "Reduced Inequalities within and among Countries."

[0035] §2 Configuration example Fig. 2 is a diagram showing a schematic configuration of the restraining mechanism in the chair according to the first embodiment of the present invention. As shown in Fig. 2, the first support 16 has a support shaft 16A at an end inserted into an upper opening of the second support 17. A stopper shaft 18A of the stopper part 18 is inserted into a lower opening of the second support 17.

[0036] The support shaft 16A has a first biasing portion 20 that biases the stopper portion 18 downward toward the floor surface F (FIG. 1). The second support 17 has a second biasing portion 21 that biases the stopper portion 18 in a direction away from the floor surface F, i.e., in an upward direction. The first biasing portion 20 and the second biasing portion 21 are composed of a biasing member such as a spring, for example. The first biasing portion 20 and the second biasing portion 21 may be composed of a single biasing member or may be composed of a plurality of biasing members. When the armrest 13 receives a downward force of a first predetermined value or more, the stopper portion 18 is pressed against the floor surface F by a combined force of the biasing force of the first biasing portion 20 and the biasing force of the second biasing portion 21. The horizontal movement of the leg portion 12 is restricted by a frictional force corresponding to the force with which the stopper portion 18 is pressed against the floor surface F. This prevents the chair 1 from moving in the horizontal direction when the user stands up, and prevents the user from falling over. The legs 12 and the stopper 18 are preferably shaped so as not to interfere with each other. For example, the stopper 18 is preferably cut out to match the shape of the legs 12. The stopper 18 may have a ground contact area with the floor surface F larger than the cross-sectional area of ​​the second support 17, as long as it does not interfere with the legs 12. In this way, the chair 1 can improve ground contact stability when the user stands up. Furthermore, the stopper 18 may be made of a friction material such as rubber, and may be shaped like a trapezoid or a suction cup with a wide bottom surface. In this way, even if the floor surface F is slippery, the legs 12 are prevented from moving in the horizontal direction, and the user is prevented from falling over.

[0037] When the downward force received by armrest 13 falls below a second predetermined value, which is equal to or less than the first predetermined value, stopper portion 18 is moved away from floor surface F by a combined force of the biasing force of first biasing portion 20 and the biasing force of second biasing portion 21. This makes it possible to move chair 1 in the horizontal direction after the user releases his / her hands from armrest 13.

[0038] Reference numeral 3000 in Fig. 3 is a schematic cross-sectional view of the first support 16 in the AA cross section in Fig. 2. Reference numeral 3001 in Fig. 3 is a schematic cross-sectional view of the second support 17 in the AA cross section in Fig. 2. The external teeth 16B of the first support 16 and the internal teeth 17A of the second support 17 have shapes that allow them to mesh with each other. The cross-sectional shape of the support shaft 16A is circular, and its diameter is large enough not to come into contact with the internal teeth 17A.

[0039] 2, the first support 16 does not have external teeth 16B in a portion 16C that is inserted into the upper opening of the second support 17 when the armrest 13 is not receiving a downward force of a predetermined value or more. As shown by reference numeral 3000 in FIG. 3, the cross-sectional shape of the portion 16C is circular, and the diameter of the portion 16C is large enough not to come into contact with the internal teeth 17A.

[0040] As shown by reference numeral 3000 in FIG. 3, the first support 16 has a hole 16D through which the pedestal post 12A of the leg 12 passes.

[0041] Reference numeral 4000 in FIG. 4 is a schematic diagram showing a seat rotation limiting member in the chair according to the first embodiment of the present invention. The receiving plate 14 shown by reference numeral 4000 in FIG. 4 is an example of a seat rotation limiting member. The receiving plate 14 shown by reference numeral 4000 in FIG. 4 has a hole 14A into which the boss 15A of the armrest fixing part 15 is inserted. The boss 15A of the armrest fixing part 15 has a sufficient length so that it does not come out of the hole 14A even when the armrest 13 receives a downward force of a predetermined value or more. Since the boss 15A does not come out of the hole 14, the rotation of the receiving plate 14 relative to the armrest 13 is limited in a state in which the rotation of the armrest 13 relative to the leg part 12 is suppressed by the meshing between the external teeth 16B of the first support 16 and the internal teeth 17A of the second support 17. This makes it possible to prevent a user who is trying to stand up by putting his / her hands on the elbow rest 13A of the armrest 13 from falling due to the rotation of the seat part 11.

[0042] The hole 14A of the receiving plate 14 may have a shape that allows the boss 15A of the armrest fixing part 15 to be inserted, and may have a range of motion in which the boss 15A moves horizontally. Reference numeral 4001 in FIG. 4 is a plan view of the receiving plate 14 shown by reference numeral 4000. The hole 14A of the receiving plate 14 shown by reference numeral 4001 in FIG. 4 is substantially the same as the boss 15A of the armrest fixing part 15. The hole 14A of the receiving plate 14 may have a range of motion for the boss 15A, such as the hole 14B shown by reference numeral 4002 in FIG. 4 and the hole 14C shown by reference numeral 4003 in FIG. Some users of the chair 1 have different hand strengths on the left and right. By providing a range of motion for the boss 15A, such as the hole 14B shown by reference numeral 4002 in FIG. 4, the user can move the armrest 13 to the side on which it is easier to apply force, and put their weight on it.

[0043] The receiving plate 14 may be adjusted to suit the physical characteristics of the user. For example, as shown by reference numeral 4004 in Fig. 4, the receiving plate 14 may be adjusted for each user using an adjustment member 14D such as a rubber bush.

[0044] [Embodiment 2] In the first embodiment, the external teeth 16B of the first support 16 abut against the internal teeth 17A of the second support 17 to prevent the armrest 13 from rotating relative to the leg 12. However, the method of preventing the armrest 13 from rotating relative to the leg 12 is not limited to the method of abutting the external teeth 16B and the internal teeth 17A.

[0045] FIG. 5 is a diagram showing a schematic configuration of a restraining mechanism in a chair according to a second embodiment of the present invention. The first support 36 and the second support 37 indicated by the reference numeral 5000 in FIG. 5 are an example of the restraining mechanism. The first support 36 is an example of the second member of the restraining mechanism, and has a columnar shape extending in the vertical direction, and the upper end is fixed to the lower surface 15B of the armrest fixing part 15. The first support 36 does not have external teeth 16B and a support shaft 16A. The first support 36 has a viscoelastic body 36A fixed to the surface facing the stopper shaft 18A.

[0046] The second support 37 is an example of a first member of the restraining mechanism, and has a cylindrical shape with an opening in the vertical direction. As shown by reference numeral 5000 in FIG. 5, when the armrest 13 is not receiving a downward force of a predetermined value or more, a part of the first support 36 is inserted into the upper opening of the second support 37. The stopper shaft 18A of the stopper portion 18 is inserted into the lower opening of the second support 37. As shown by reference numeral 5000 in FIG. 5, when the armrest 13 is not receiving a downward force of a predetermined value or more, the first support 36 is not in contact with the stopper shaft 18A.

[0047] When the armrest 13 receives a downward force of a predetermined value or more, the first support 36 moves downward together with the armrest fixing part 15. As shown by reference numeral 5001 in FIG. 5, the viscoelastic body 36A is pressed against the stopper shaft 18A by the downward force received by the armrest 13, and is viscoelastically deformed to contract in the vertical direction and extend in the horizontal direction, thereby contacting the inner surface of the second support 37. At this time, the rotation of the armrest fixing part 15 and the armrest 13, which are integrated with the first support 16, relative to the leg 12 is inhibited by friction between the viscoelastic body 36A of the first support 16 and the inner surface of the second support 37. In the inhibiting mechanism using the external teeth 16B and the internal teeth 17A, the angle of the armrest 13 relative to the leg 12 is limited to the meshing angle of the external teeth 16B and the internal teeth 17A. However, with the restraining mechanism using the viscoelastic body 36A, it is possible to restrain the armrest fixing part 15 and the armrest 13 from rotating relative to the leg 12 regardless of the angle at which the armrest 13 is at relative to the leg 12.

[0048] [Embodiment 3] In the first or second embodiment, the horizontal movement of the leg 12 is limited by pressing the stopper 18 against the floor surface F. However, the method of limiting the horizontal movement of the leg 12 is not limited to the method of pressing the stopper 18 against the floor surface F.

[0049] FIG. 6 is a diagram showing a schematic configuration of a restraining mechanism in a chair according to a third embodiment of the present invention. Reference numeral 6000 in FIG. 6 is a schematic configuration diagram of a locking member 51 provided on a caster 12B of a leg 12. As shown by reference numeral 6000 in FIG. 6, the locking member 51 has a connection member 52, a friction member 53, and a rotation shaft 54. In the state shown by reference numeral 6000 in FIG. 6, the locking member 51 is in a first state in which the leg 12 is allowed to move in the horizontal direction. The connection member 52 is, for example, a wire, and has a property of being deformed by a force applied in the vertical direction and returning to its original shape when the force applied in the vertical direction is removed.

[0050] Reference numeral 6001 in FIG. 6 indicates a wiring example of the connection member 52 when the locking member 51 is in the first state. In reference numeral 6001 in FIG. 6, the connection member 52 penetrates the side surface of the cylindrical second member 17 and reaches the inside of the second member 17. The locking member 51 is provided for each caster 12B of the leg 12, and the connection member 52 of each locking member 51 is connected inside the second member 17. When the downward force received by the armrest 13 becomes equal to or greater than a first predetermined value, as shown by reference numeral 6003 in FIG. 6, the support shaft 16A of the first member 16 moves downward, and pushes down the connection member 52 of each locking member 51 downward. When the connection member 52 is pushed down inside the second member 17, the locking member 51 moves in conjunction with the force in the direction 60 toward the second member 17.

[0051] Reference numeral 6002 in Fig. 6 indicates a second state in which the locking member 51 locks the leg 12 from moving in the horizontal direction. When the locking member 51 is pulled in the direction 60 by the connecting member 52, it rotates about the rotation axis 54. This rotation causes the friction member 53 of the locking member 51 to be pressed against the caster 12B, and the caster 12B is locked by the friction force generated between the friction member 53 and the connecting member 52. In other words, when the connecting member 52 is pressed down inside the second member 17, the locking member 51 transitions from the first state to the second state in conjunction with this.

[0052] In the above, an example in which the connecting member 52 is made of a wire has been described, but the present invention is not limited to this. For example, the connecting member 52 may be made of a rod-shaped rigid body, and the locking member 51 may be moved in response to the movement of the first member 16.

[0053] The locking member 51 may also have a biasing member that biases the friction member 53 so as to move away from the caster 12B of the leg 12. For example, a coil spring may be provided around the rotation shaft 54 ​​of the locking member 51 to bias the friction member 53 so as to move away from the caster 12B of the leg 12. When the downward force received by the armrest 13 becomes equal to or greater than a first predetermined value, the support shaft 16A of the first member 16 moves downward against the biasing force of the coil spring, pushing the connection members 52 of the locking members 51 downward, and the locking member 51 transitions from the first state to the second state. On the other hand, when the downward force received by the armrest 13 becomes equal to or less than a second predetermined value that is equal to or less than the first predetermined value, the biasing force of the coil spring transitions the locking member 51 from the second state to the first state.

[0054] [Embodiment 4] In the first embodiment, the first support 16 is provided with the external teeth 16B, and the second support 17 is provided with the internal teeth 17A. However, the first support 16 may be provided with the internal teeth, and the second support 17 may be provided with the external teeth.

[0055] Fig. 7 is a diagram showing a schematic configuration of a restraining mechanism in a chair according to a fourth embodiment of the present invention. A first support 71 shown in Fig. 7 is an example of a second member of the restraining mechanism, and has a cylindrical shape. An upper opening of the first support 71 is covered by the lower surface 15B of the armrest fixing part 15. A support shaft 73 is fixed to the lower surface 15B of the armrest fixing part 15 and is inserted into the upper opening of the first support 71. The first support 71 has internal teeth 71A.

[0056] The second support 72 is an example of a first member of the restraining mechanism, and has a cylindrical shape with an opening in the vertical direction. A stopper shaft 74A of the stopper portion 74 is inserted into the lower opening of the second support 72. An external tooth 74B is connected to the upper end of the stopper shaft 74A. A part of the first support 71 is inserted into the upper opening of the second support 72. The stopper portion 74 and the external tooth 74B are provided so as not to rotate with respect to the leg portion 12. A first biasing portion (not shown) is provided between the support shaft 73 and the stopper shaft 74A, and biases the stopper shaft 74A downward. In addition, a second biasing portion (not shown) is provided between the second support 72 and the stopper shaft 74A, and biases the stopper shaft 74A upward.

[0057] When the armrest 13 receives a downward force equal to or greater than a first predetermined value, the armrest fixing part 15 and the first support 71 move downward. This movement causes the internal teeth 71A of the first support 71 to come into contact with the external teeth 74B of the second support 72, preventing the first support 71, the armrest fixing part 15, and the armrest 13 from rotating relative to the leg 12.

[0058] §3 Variations In the above embodiment, the first supports 16 and 36 are located above the second supports 17 and 37. However, the first supports 16 and 36, which are an example of the second member of the restraining mechanism, may be located below the second supports 17 and 37, which are an example of the first member of the restraining mechanism.

[0059] In the above-mentioned embodiment 1, the first support 16 has the support shaft 16A at the end inserted into the upper opening of the second support 17. However, the first support 16 does not have to be provided with the support shaft 16A. When the first support 16 is not provided with the support shaft 16A, it is sufficient to provide the first biasing portion 20 between the end where the support shaft 16A was provided and the stopper shaft 18A.

[0060] In the above embodiment, the legs 12 have casters 12B and can move horizontally, but they do not have to have a structure for moving horizontally. If the legs 12 do not have a structure for moving horizontally, the chair 1 does not need to be provided with a mechanism for preventing the horizontal movement of the legs 12, such as the stopper 18, the locking member 51, etc.

[0061] In the above embodiment, the boss 15A of the armrest fixing part 15 protrudes upward and is inserted into the hole 14A of the receiving plate 14, so that the armrest 13 and the armrest fixing part 15 rotate together with the seat part 11 and the receiving plate 14 relative to the leg part 12. However, the structure for integrating the armrest fixing part 15 and the receiving plate 14 to rotate relative to the leg part 12 is not limited to the boss 15A of the armrest fixing part 15 and the hole 14A of the receiving plate 14. For example, a boss may protrude downward from the seat part 11 or the receiving plate 14 and be inserted into a hole provided in the armrest fixing part 15 or the restraining mechanism (for example, the upper one of the first support 16 and the second support 17).

[0062] In the above embodiment, the first supports 16 and 36 have a columnar shape extending in the vertical direction, but are not limited to this. For example, the first supports 16 and 36 may have a cylindrical shape like an oil-free bushing.

[0063] Reference numeral 8000 in FIG. 8 is a schematic diagram of a restraining mechanism formed using an oil-free bush. The first support 90 shown by reference numeral 8000 in FIG. 8 has a plurality of holes 91 on its side. Self-lubricating members 92 are embedded in the plurality of holes 91. The self-lubricating members 92 are composed of bearings, solid lubricants, etc. As shown by reference numeral 8001 in FIG. 8, the self-lubricating members 92 of the first support 90 abut against the inner side surface of the second support 37. In this way, at least a part of the first support 90 abuts against the second support 37, so that the shaking of the armrest 13 when it moves up and down can be reduced.

[0064] In the above embodiment, the boss 15A of the armrest fixing part 15 has a sufficient length not to come out of the hole 14A of the receiving plate 14 even when the armrest 13 receives a downward force of a predetermined value or more. However, the boss 15A of the armrest fixing part 15 may come out of the hole 14A of the receiving plate 14 when the armrest 13 receives a downward force of a predetermined value or more. For example, when the range in which the seat part 11 can rotate relative to the leg part 12 is sufficiently narrow, even if the rotation of the seat part 11 and the receiving plate 14 is not restricted relative to the armrest 13 and the armrest fixing part 15, a user who is trying to stand up by putting his hands on the elbow rest 13A of the armrest 13 is unlikely to fall due to the rotation of the seat part 11, and stability can be maintained.

[0065] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention.

[0066] 〔summary〕 The chair of aspect 1 of the present invention comprises a seat, legs supporting the seat, a receiving member that receives force applied downward by a user, a rotation mechanism that rotates the receiving member relative to the legs, and a restraining mechanism that prevents rotation of the receiving member by the rotation mechanism, wherein the restraining mechanism comprises a cylindrical first member having an opening in the vertical direction, and a second member that is inserted into the opening of the first member and abuts against the inner surface of the first member when the receiving member receives a force equal to or greater than a first predetermined value, thereby preventing rotation of the receiving member relative to the legs.

[0067] A chair according to aspect 2 of the present invention is the chair described in aspect 1, further comprising a seat rotation limiting member that limits the rotation of the seat relative to the receiving member when rotation of the receiving member is prevented by the restraining mechanism.

[0068] A chair according to aspect 3 of the present invention is a chair as described in aspect 1 or 2, wherein one of the first member and the second member has internal teeth and the other has external teeth, and the restraining mechanism prevents rotation of the receiving member relative to the leg by causing the external teeth to abut against the internal teeth when the receiving member receives a force equal to or greater than the first predetermined value.

[0069] A chair according to aspect 4 of the present invention is a chair as described in aspect 1 or 2, in which the second member has a viscoelastic body, and the restraining mechanism prevents rotation of the seat relative to the legs by elastically deforming the viscoelastic body in response to the force received by the receiving member and the viscoelastic body abutting the inner surface of the first member.

[0070] A chair according to aspect 5 of the present invention is a chair described in any one of aspects 1 to 4, wherein the legs are movable horizontally relative to the floor surface, and the restraining mechanism further restrains horizontal movement of the legs when the receiving member receives a force equal to or greater than the first predetermined value.

[0071] A chair according to a sixth aspect of the present invention is the chair described in the fifth aspect, wherein the restraining mechanism further has a stopper shaft, and one of the first member and the second member has a first biasing member that biases the stopper shaft toward the floor surface, and the other has a second biasing member that biases the stopper shaft in a direction away from the floor surface, and when the receiving member receives a force equal to or greater than the first predetermined value, the stopper shaft is pressed against the floor surface by the combined force of the biasing force of the first biasing member and the biasing force of the second biasing member, thereby restraining the horizontal movement of the leg, and when the receiving member receives a force less than a second predetermined value that is less than the first predetermined value, the stopper shaft is moved away from the floor surface by the combined force of the biasing force of the first biasing member and the biasing force of the second biasing member.

[0072] A chair according to aspect 7 of the present invention is the chair described in aspect 5, wherein the restraining mechanism causes either the first member or the second member to move up and down in response to a force received by the receiving member, and the restraining mechanism has a locking member arranged on the leg and capable of transitioning between a first state that allows the leg to move horizontally and a second state that prevents the leg from moving horizontally, and a connecting member that links the locking member to the movement of one of the first member and the second member that moves up and down in response to the force received by the receiving member, and when the receiving member receives a force equal to or greater than the first predetermined value, the locking member transitions from the first state to the second state. [Explanation of symbols]

[0073] 1 Chair 11 Seat 12 Legs 12B Caster 12C Seat rotation mechanism 13 Armrest 13A Armrest 15 Armrest fixing part 15A Boss 16, 36, 71 1st support 16B, 74B external teeth 17, 37, 72 Second support 17A, 71A internal teeth 18A, 74A Stopper shaft 18, 74 Stopper part 20 First biasing section 21 Second biasing section 36A Viscoelastic body 51 Locking member 52 Connection parts 53 Friction materials 54 Rotation axis

Claims

1. A seat portion, A leg portion supporting the seat portion; A receiving member that receives a force applied downward by a user; A rotation mechanism that rotates the receiving member relative to the leg portion; a suppression mechanism that suppresses rotation of the receiving member by the rotation mechanism, The suppression mechanism includes: A cylindrical first member having an opening in the vertical direction; a second member that is inserted into the opening of the first member and abuts against the inner surface of the first member when the receiving member receives a force equal to or greater than a first predetermined value, thereby preventing the receiving member from rotating relative to the leg.

2. The chair according to claim 1 , further comprising a seat rotation limiting member that limits rotation of the seat relative to the receiving member when rotation of the receiving member is prevented by the preventing mechanism.

3. one of the first member and the second member has internal teeth and the other has external teeth; The chair according to claim 1 or 2, wherein the restraining mechanism prevents rotation of the receiving member relative to the leg by causing the outer teeth to abut against the inner teeth when the receiving member receives a force equal to or greater than the first predetermined value.

4. The second member has a viscoelastic body, The chair of claim 1 or 2, wherein the restraining mechanism prevents rotation of the seat relative to the legs by elastically deforming the viscoelastic body in response to the force received by the receiving member and by the viscoelastic body abutting the inner surface of the first member.

5. The leg is movable horizontally relative to a floor surface, The chair according to claim 1 or 2, wherein the restraining mechanism further restrains horizontal movement of the leg when the receiving member receives a force equal to or greater than the first predetermined value.

6. The restraining mechanism further includes a stopper shaft. one of the first member and the second member has a first biasing member that biases the stopper shaft toward the floor surface, and the other has a second biasing member that biases the stopper shaft in a direction away from the floor surface, When the receiving member receives a force equal to or greater than the first predetermined value, the stopper shaft is pressed against the floor surface by a combined force of the biasing force of the first biasing member and the biasing force of the second biasing member, thereby suppressing horizontal movement of the leg portion, The chair of claim 5, wherein when the receiving member receives a force less than a second predetermined value that is less than the first predetermined value, the stopper shaft is moved away from the floor surface by a combined force of the biasing force of the first biasing member and the biasing force of the second biasing member.

7. The restraining mechanism moves either the first member or the second member up or down in response to the force received by the receiving member, The suppression mechanism includes: a locking member disposed on the leg portion and capable of transitioning between a first state in which the leg portion is permitted to move in a horizontal direction and a second state in which the leg portion is prevented from moving in the horizontal direction; a connecting member that links the locking member to the movement of one of the first member and the second member that moves up and down in response to a force received by the receiving member, The chair described in claim 5, wherein when the receiving member receives a force equal to or greater than the first predetermined value, the locking member transitions from the first state to the second state by linking the locking member to one of the first member and the second member via the connecting member.

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