chair

Abstract

The present invention provides a chair that allows for the appropriate setting of the reaction force against the backward tilting movement of the back support. [Solution] The chair is equipped with a reaction force adjustment mechanism G that varies the reaction force of the first compression reaction spring K in response to the backward tilting motion of the back support D. The reaction force adjustment mechanism G generates an upright reaction force on the back support D by compressing the first compression reaction spring K in accordance with the rotational motion of the back support D, and changes the magnitude of the reaction force by changing the position of the connecting member P in a direction that intersects the axis f of the first compression reaction spring K.

Description

Technical Field

[0001] The present invention relates to a chair.

Background Art

[0002] It is well known that some known chairs are provided with a reaction spring that applies a reaction force to return to the original position with respect to the reclining movement of the backrest. Furthermore, in this type of chair, there are various configurations in which the degree of reaction force against the reclining movement of the backrest can be changed by changing the inclination of the reaction spring (for example, see Patent Document 1).

[0003] However, in such a configuration, since the inclination of the reaction spring is different in each of two or more different reaction force setting states, the reaction force characteristics of the reaction spring are also changed. Therefore, in the conventional configuration, it has not always been possible to suitably set the reaction force against the reclining movement of the back support.

[0004] Furthermore, in the conventional configuration, since the rotation knob for adjusting the reaction force is provided at a position that directly receives the biasing force of the reaction spring (that is, one end of the reaction spring), a corresponding force is required to move the operation part while resisting the biasing force of the reaction spring, and there is also a problem that it cannot be operated easily.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] The present invention has been made paying attention to the above circumstances, and at least an object thereof is to provide a chair capable of suitably setting the reaction force against the reclining movement of the back support. [Means for solving the problem]

[0007] In other words, the present invention has the following configuration.

[0008] The invention described in claim 1 is a chair comprising a support base, a back support rotatably supported with respect to the support base, and a compression reaction spring that generates a reaction force in the upright direction of the back support when compressed in conjunction with the backward tilting movement of the back support, wherein the front end of the compression reaction spring is supported by a front structure so as to be movable relative to the support base and the rear end is supported by a rear structure, and a reaction force adjustment mechanism is provided to vary the reaction force of the compression reaction spring in relation to the backward tilting movement of the back support, the reaction force adjustment mechanism includes a connecting member that is connected to the support base by the front structure and connected to the back support by an engagement structure, and generates an upright reaction force on the back support by compressing the compression reaction spring in conjunction with the rotational movement of the back support, and the magnitude of the reaction force is changed by changing the position of the connecting member in a direction intersecting the axis of the compression reaction spring.

[0009] The invention described in claim 2 is the chair according to claim 1, wherein the front structure includes a rotating member having one end rotatably supported with respect to the support base and the other end, and the front end of the compression reaction spring and the front end of the connecting member are rotatably engaged with the other end of the rotating member excluding the one end.

[0010] The invention described in claim 3 is the chair according to claim 2, wherein, when the back support is unloaded, the rotating member abuts against a part of the support base or a locking member attached to the support base.

[0011] The invention described in claim 4 is the chair according to claim 1, wherein the front structure has a slide guide provided on the support base and a slider that is movable guided by the slide guide, and the front end of the compression reaction spring and the front end of the connecting member are engaged with the slider.

[0012] The invention described in claim 5 is the chair according to claim 4, wherein, when the back support is unloaded, the slider abuts against a part of the support base or a locking member attached to the support base.

[0013] The invention described in claim 6 is the chair according to claim 1, wherein the rear structure rotatably supports the rear end of the compression reaction spring on the support base.

[0014] The invention described in claim 7 is the chair according to claim 4 or 5, wherein the rear structure fixes the rear end of the compression reaction spring to the support base in a way that prevents it from moving, and the direction in which the slide guide extends coincides with the direction of the axis of the compression reaction spring.

[0015] The invention described in claim 8 is the chair according to claim 1, wherein the engagement structure allows the position of the connection between the rear end of the connecting member and the back support to be changed to two or more different positions at a distance from the rotation center of the back support.

[0016] The invention described in claim 9 is the chair according to claim 8, wherein the rear end of the connecting member is an engagement pin, the connecting portion of the back support is an engagement guide extending in an arc shape from the front end of the connecting member, and the engagement pin is changeably engaged with the engagement guide at two or more different positions.

[0017] The invention described in claim 10 is a chair according to claim 8 or 9, wherein the reaction force adjustment mechanism is configured such that, when the back support is unloaded, the axis of the compression reaction spring extends at the same angle with respect to the horizontal line even when the position of the connecting member is changed.

[0018] The invention according to claim 11 is the chair according to claim 3, which is configured such that, when the backrest support is unloaded, the reaction force of the compression reaction spring does not act on the connecting member.

[0019] The invention according to claim 12 is the chair according to claim 8, which has an operating mechanism for changing the position of the rear end portion of the connecting member and the connecting portion of the backrest support in a direction intersecting the axial center line by transmitting an operating force applied by the user.

[0020] The invention according to claim 13 is the chair according to claim 1, in which, between the backrest support and the support base, another reaction spring that is provided separately from the compression reaction spring and generates a reaction force against the backward tilting movement of the backrest support is interposed.

[0021] The invention according to claim 14 is the chair according to claim 13, in which, when the backrest support is unloaded, the compression reaction spring becomes its natural length, and the other reaction spring biases the backrest support in a direction away from the support base.

Advantages of the Invention

[0022] As described above, according to the present invention, it is possible to provide a chair that can preferably set at least the reaction force against the backward tilting movement of the backrest support.

Brief Description of the Drawings

[0023] [Figure 1] Perspective view for explaining an embodiment of the present invention. [Figure 2] Enlarged perspective view of the main part in the same embodiment. [Figure 3] Front view of the main part in the same embodiment. [Figure 4] Rear view of the main part in the same embodiment. [Figure 5] Right side view of the main part in the same embodiment. [Figure 6] Left side view of the main part in the same embodiment. [Figure 7] Plan view of the main part in the same embodiment. [Figure 8] A bottom view of the main part of the same embodiment. [Figure 9] A diagram illustrating the operation of the same embodiment. [Figure 10] A diagram illustrating the operation of the same embodiment. [Figure 11] A diagram illustrating the operation of the same embodiment. [Figure 12] A diagram illustrating the operation of the same embodiment. [Figure 13] A diagram illustrating the operation of the same embodiment. [Figure 14] A diagram illustrating the operation of the same embodiment. [Figure 15] A diagram illustrating the operation of the same embodiment. [Figure 16] A diagram illustrating the operation of the same embodiment. [Figure 17] A diagram illustrating the operation of the same embodiment. [Figure 18] A diagram illustrating the operation of the same embodiment. [Figure 19] A perspective view showing other actual configurations. [Figure 20] Left side view showing other actual configurations. [Figure 21] Left side view showing other actual configurations. [Figure 22] Left side view showing other actual configurations. [Modes for carrying out the invention]

[0024] One embodiment of the present invention will be described below with reference to Figures 1 to 18.

[0025] This embodiment applies the present invention to a swivel chair for office use (hereinafter simply referred to as "chair") that is suitably used in offices and the like.

[0026] The chair comprises legs A, a support base B attached to the upper end of legs A, a seat (not shown) placed on the support base B, a back support D rotatably supported relative to the support base B via a main shaft j1, and a backrest (not shown) attached to the back support D.

[0027] The chair is equipped with a reaction force transmission mechanism H that acts in response to the backward tilting motion of the back support D. The chair is also equipped with a reaction force adjustment mechanism G that can adjust the reaction force in response to the backward tilting motion of the back support D to two or more different values.

[0028] The chair in this embodiment will be described in detail below.

[0029] <<Legs A>> Leg A comprises multiple leg blades a1, each having a caster at its tip, and leg supports a2 erected at the base ends of the leg blades a1.

[0030] <<Support base B>> Support base B supports the back support D, the backrest, and the seat.

[0031] The support base B is configured to be rotatable relative to the floor surface together with the leg support column a2. The support base B is made of metal or synthetic resin and is connected to the upper end of the leg support column a2. The support base B has an internal storage space and is box-shaped with an open top.

[0032] The support base B comprises a foundation bottom wall portion b11 that connects to the leg support column a2, an inclined bottom wall portion b12 extending diagonally downward and forward from the front end of the foundation bottom wall portion b11, a front bottom wall portion b13 extending forward from the front end of the inclined bottom wall portion b12 and inclined to gradually move upward as it moves forward, left and right side walls b2 extending upward from both the left and right ends of the foundation bottom wall portion b11, the inclined bottom wall portion b12, and the front bottom wall portion b13, a front wall b3 connecting the front parts of the left and right side walls b2, and a rear wall b4 connecting the rear parts of the left and right side walls b2.

[0033] In other words, the support base B comprises a bottom wall portion b1 composed of a foundation bottom wall portion b11, an inclined bottom wall portion b12, and a front bottom wall portion b13; left and right side walls b2 extending upward from both left and right ends of the bottom wall portion b1; a front wall b3 erected at the front of the bottom wall portion b1; and a rear wall b4 erected at the rear of the bottom wall portion b1.

[0034] Support base B is covered on the outside with a cover (not shown) to form a suitable appearance, if necessary.

[0035] <<Seat (not shown)>> The seat has a seating surface on which a person sits. The seat is supported by a support base B via a seat support mechanism (not shown).

[0036] <<Back support D>> The back support D is rotatably supported relative to the support base B via the main axis j1, which is the axis.

[0037] The back support D is configured to rotate between a normal position (L), which is an unloaded position where no weight is applied by the seated person, and a reclined position (J), which is more reclined than the normal position (L).

[0038] The back support D is biased in the upright direction, i.e., the direction in which it takes the normal position (L), by a first compression reaction spring K, which is a compression reaction spring, and a second compression reaction spring M, which is another reaction spring.

[0039] The back support D receives the backrest and load from the seated person, causing the first compression reaction spring K and the second compression reaction spring M, which are other reaction springs, to compress against the biasing force, allowing the back support D to move from a normal position (L) to a reclined position (J).

[0040] The back support D comprises left and right side plates d1 that are in the shape of upright plates extending in the front-rear direction and are arranged in pairs parallel to each other on the left and right sides; a rear connecting member d2 that extends in the left-right direction and connects the rear portions of the left and right side plates d1; a spring receiving shaft j3 which is a front connecting member that extends in the left-right direction and connects the portions of the left and right side plates d1 that are located below the main shaft j1; and an intermediate connecting member d3 which is arranged in front of the rear connecting member d2 and connects the left and right side plates d1.

[0041] <Left and right side panels d1> The left and right side plates d1 hold a main shaft j1 that extends in the left-right direction, allowing the entire back support D to rotatably support the support base B. The main shaft j1 is interposed between the support base B and the back support D. The main shaft j1 is inserted through a main shaft insertion hole h1 provided in the left and right side plates d1.

[0042] The left and right side plates d1 are provided with engaging portions h2 into which engaging shafts j5, also called engaging pins, which extend in the left-right direction, engage. The engaging shafts j5 are interposed between the back support D and the connecting member P.

[0043] The engaging portion h2 is located above the portion of the left and right side plates d1 that holds the main shaft j1. The engaging portion h2 is located along a virtual arc drawn with the front shaft j4 as the center point.

[0044] In this embodiment, the engaging portion h2 is shaped like an elongated hole extending in a partial arc along a virtual arc with the front shaft j4 as its center point. The engaging portion h2 holds the engaging shaft j5 so that it can move in the vertical direction. That is, the elongated engaging portion h2 can hold the engaging shaft j5 so that the distance between the engaging shaft j5 and the main shaft j1 can be changed.

[0045] In this embodiment, the back support D is provided with a stop mechanism E that stops the engaging shaft j5 with the engaging portion h2. The stop mechanism E will be described in detail later.

[0046] <Spring bearing shaft j3> The spring support shaft j3 constitutes the lower part of the back support D. The spring support shaft j3 is positioned below the portion of the back support D that holds the main shaft j1. The spring support shaft j3 is installed between the lower parts of the left and right side plates d1 of the back support D. The rear end of the second compression reaction spring M is rotatably connected to the spring support shaft j3. The front end of the second compression reaction spring M is supported by the support base B via the support shaft j2.

[0047] In other words, the spring bearing axis j3 of the back support D is always biased backward, that is, always in the direction in which the back support D assumes its normal posture (L), by a second compression reaction spring M that generates a reaction force using the support base B as a foothold.

[0048] <<Backrest (not shown)>> The backrest has a backrest surface that supports the seated person's back from behind. The backrest is attached to the back support D by an appropriate method.

[0049] <<Reaction Force Transmission Mechanism H>> The reaction force transmission mechanism H, in conjunction with the backward tilting movement of the back support D, uses a connecting member P to pull the front end of the first compression reaction spring K backward, thereby generating a reaction force in the first compression reaction spring K and transmitting that reaction force to the back support D.

[0050] Furthermore, since the configuration of the reaction force transmission mechanism H is included in the configuration of the reaction force adjustment mechanism G, details will be shown in the explanation of the reaction force adjustment mechanism G.

[0051] <<Reaction force adjustment mechanism G>> The reaction force adjustment mechanism G is located between the back support D and the support base B. The reaction force adjustment mechanism G allows the user to adjust the strength of the reaction force against the backward tilting movement of the back support D.

[0052] The reaction force adjustment mechanism G allows the user to select one of five pre-set, distinct reaction force settings, namely, the first reaction force setting state S1, the second reaction force setting state S2, the third reaction force setting state S3, the fourth reaction force setting state S4, and the fifth reaction force setting state S5, through their operation.

[0053] The reaction force adjustment mechanism G includes a first compression reaction spring K, which extends in the front-rear direction and generates a reaction force against the backward tilting movement of the back support D; a second compression reaction spring M, which extends in the front-rear direction and generates a reaction force against the backward tilting movement of the back support D; an intermediate member N that is rotatably supported in the front-rear direction on the support base B via a pivot shaft j2; and a front shaft j4 that extends in the front-rear direction and whose front end engages with the upper part of the intermediate member N, while its rear end engages with the back support D via an engagement shaft j5. The device comprises a connecting member P that connects the front end of the first compression reaction spring K and the back support D by engaging with the joint portion h2, a detent mechanism E that detently engages an engagement shaft j5 interposed between the connecting member P and the back support D at a predetermined position on the engagement portion h2, and a reaction force adjustment lever Q, which is an operating means that transmits an operating force from the user to the engagement shaft j5, thereby changing the position of the engagement shaft j5 interposed between the connecting member P and the back support D in a direction intersecting the axis f of the first compression reaction spring K.

[0054] The reaction force adjustment mechanism G is configured to allow the separation distance between the engagement shaft j5, which engages with the back support D, and the main shaft j1, which is the rotation center of the back support D, to be changed to five different separation distances.

[0055] In this embodiment, the user can selectively change the distance between the engaging shaft j5 and the support shaft j2 to five different distances by operating the reaction force adjustment lever Q to move the engaging shaft j5, which is locked in place at a predetermined location on the engaging portion h2 by the locking mechanism E, in the vertical direction.

[0056] In other words, the reaction force adjustment mechanism G has a connecting member P that connects to the support base B by a front structure including a front shaft j4 and an intermediate member N, and connects to the back support D by an engagement structure including an engagement shaft j5 and an engagement part h2. The reaction force adjustment mechanism G compresses the first compression reaction spring K in accordance with the rotational movement of the back support D in the direction of a backward tilting posture (J) around the main shaft j1, thereby generating a reaction force in the upright direction, i.e., the normal posture (L) direction, on the back support D. The reaction force adjustment mechanism G changes the magnitude of the reaction force that tries to return to the normal posture (L) direction by changing the position of the connecting member P in a direction that intersects the axis line f of the first compression reaction spring K.

[0057] Here, the "front structure" is composed of an intermediate member N, which is a rotating member having one end, i.e., the lower end, rotatably supported by a support base B via a pivot shaft j2, and the other end, i.e., the upper end. In the "front structure," the front end of the first compression reaction spring K and the front end of the connecting member P are rotatably engaged with the upper end side of the intermediate member N, excluding the lower end, via a front shaft j4, which is an intermediary component.

[0058] Furthermore, the "engagement structure" is a structure that allows the position of the engagement shaft j5 interposed between the rear end of the connecting member P and the back support D, i.e., the connection between the connecting member P and the back support D, to be changed to two or more different positions (in this embodiment, five different vertical positions). The "engagement structure" allows the user to selectively set the distance between the engagement shaft j5 and the main shaft j1 so that it can take on five different distance relationships.

[0059] <First compression reaction spring K> The first compression reaction spring K is composed of a compression coil spring. The first compression reaction spring K is provided separately from the second compression reaction spring M. The first compression reaction spring K is positioned above the second compression reaction spring M. The first compression reaction spring K generates a reaction force against the backward tilting movement of the back support D.

[0060] The front end of the first compression reaction spring K is provided with a structure capable of holding the front shaft j4. The front end of the first compression reaction spring K is rotatably supported via the front shaft j4 with respect to an intermediate member N pivotally supported on a support base B.

[0061] The rear end of the first compression reaction spring K has a structure that can hold the main shaft j1. The rear end of the first compression reaction spring K is supported by the support base B via the main shaft j1.

[0062] The first compression reaction spring K constantly biases the front shaft j4, which is held by the intermediate member N using the support base B that supports the main shaft j1 as a base, forward so that the back support D can assume the normal position (L) when unloaded. In other words, the first compression reaction spring K generates a reaction force that causes the back support D to return from the reclined position (J) to the normal position (L).

[0063] The first compression reaction spring K has its rear end supported by a rear structure on a support base B. Here, the "rear structure" is a structure that rotatably supports the rear end of the first compression reaction spring K on the support base B. In this embodiment, a main shaft j1 is interposed between the support base B and the rear end of the first compression reaction spring K, allowing them to rotate relative to each other.

[0064] <Second compression reaction spring M> The second compression reaction spring M is composed of a compression coil spring. The second compression reaction spring M is interposed between the back support D and the support base B, separately from the first compression reaction spring K. The second compression reaction spring M is positioned below the first compression reaction spring K. The second compression reaction spring M generates a reaction force against the backward tilting movement of the back support D.

[0065] The rear end of the second compression reaction spring M has a structure that can hold the spring support shaft j3. The rear end of the second compression reaction spring M is connected to the spring support shaft j3 of the back support D.

[0066] The front end of the second compression reaction spring M has a structure that can hold the support shaft j2. The front end of the second compression reaction spring M is supported by the support base B via the support shaft j2.

[0067] The second compression reaction spring M constantly biases the spring-receiving shaft j3 of the back support D backward, using the support base B that supports the support shaft j2 as a foothold, so that the back support D can assume its normal position (L) when unloaded. In other words, the second compression reaction spring M generates a reaction force that causes the back support D to return from a reclined position (J) to its normal position (L).

[0068] Furthermore, the first compression reaction spring K and the second compression reaction spring M are arranged so as to be substantially parallel when viewed from the side when the back support D is unloaded.

[0069] <Intermediate component N> The intermediate member N is a plate-shaped member that extends in the vertical direction. The lower end of the intermediate member N is rotatably supported on the support base B via a support shaft j2. The upper end of the intermediate member N is rotatably connected to the connecting member P and the first compression reaction spring K via a front shaft j4.

[0070] The lower end of the intermediate member N, which is the base end, is provided with a support shaft insertion hole n2 that penetrates in the left-right direction, and the upper end, which is the tip end, is provided with a front shaft insertion hole n1 that penetrates in the left-right direction.

[0071] Here, the support shaft j2 connecting the intermediate member N and the support base B is also interposed between the second compression reaction spring M and the support base B. In other words, the support shaft j2 functions as a spring support that receives the front end of the second compression reaction spring M.

[0072] The front shaft j4 is interposed between the first compression reaction spring K and the intermediate member N. The front shaft j4 also functions as a spring support that receives the front end of the first compression reaction spring K. The front shaft j4 is located above the main shaft j1 and the support shaft j2.

[0073] <Connecting member P> The connecting member P extends in the front-rear direction. In this embodiment, the connecting member P connects the front end of the first compression reaction spring K to the back support D.

[0074] The connecting member P has a front shaft holding hole (not shown) that penetrates in the left-right direction for holding a front shaft j4 that extends in the left-right direction at its front end, and an engagement shaft holding hole (not shown) that penetrates in the left-right direction for holding an engagement shaft j5 that extends in the left-right direction at its rear end.

[0075] The connecting member P has its front end connected via a front axis j4 to the front end of the first compression reaction spring K, which extends in the front-rear direction, and to the upper end of the intermediate member N, while its rear end engages with the back support D via an engagement axis j5.

[0076] The engaging shaft j5, held in the engaging shaft holding hole of the connecting member P, engages with a vertically extending, elongated engaging portion h2 provided in the back support D. The engaging portion h2 and the engaging shaft j5 are located above the main shaft j1.

[0077] <Engagement axis j5> The engaging shaft j5 is cylindrical and extends linearly in the left-right direction. The engaging shaft j5 engages with the engaging portion h2, which is elongated and extends in the up-down direction.

[0078] When there is no load on the back support D, the engaging shaft j5 is pressed against the rear edge of the hole in the engaging portion h2 by the ring spring C that constitutes the restraint mechanism E.

[0079] The engaging shaft j5 is configured to move vertically within the engaging portion h2 against the biasing force of the damping mechanism E in response to the user's operation of the reaction force adjustment lever Q. The engaging shaft j5 is repositionable in a direction intersecting the axis f of the first compression reaction spring K. In this embodiment, the engaging shaft j5 is repositionable in a direction substantially perpendicular to the axis f of the first compression reaction spring K.

[0080] <Moderation mechanism E> The locking mechanism E mainly consists of a ring spring C, which is a spring member made of synthetic resin, attached near the engaging portion h2 on the left and right side plates d1, and an engaging portion h2 that holds the engaging shaft j5, which is biased by the ring spring C, so that it can move in the vertical direction.

[0081] The locking mechanism E biases the engaging shaft j5 rearward with a ring spring C, which is a spring member, thereby allowing the engaging shaft j5 to be positioned at one of five different vertical positions within the elongated engaging portion h2.

[0082] The ring spring C is provided with five engagement recesses c1 arranged vertically, which work in cooperation with the engagement portion h2 to hold the engagement shaft j5 in a predetermined position.

[0083] In the left and right side plates d1, a shaft hole h3 is provided in the portion behind the engagement portion h2, extending in the left-right direction. A reaction force adjustment lever Q is rotatably supported in the shaft hole h3 formed in the left and right side plates d1, for the operation of selecting one of five different engagement shaft arrangement locations set in the engagement portion h2. That is, the five engagement shaft arrangement locations are arranged side by side in the vertical direction within the engagement portion h2.

[0084] <Reaction force adjustment lever Q (operating means)> The reaction force adjustment lever Q, which is an operating means, allows the reaction force against the backward tilting movement of the back support D to be changed by the force applied by the user's hand. The reaction force adjustment lever Q engages with an engagement shaft j5, which is movably disposed within the engagement portion h2 of the back support D, thereby changing the position of the engagement shaft j5 to a predetermined position.

[0085] The reaction force adjustment lever Q is rotatably supported on the back support D. The reaction force adjustment lever Q is designed so that the user can change the distance between the engaging shaft j5, which is held in the engaging portion h2 of the back support D, and the support shaft j2 by rotating the operating end of the lever Q with the user's hand.

[0086] The reaction force adjustment lever Q comprises a lever body q1 extending in the left-right direction, and an arm portion q2 extending forward from the base end of the lever body q1 and engaging with the engagement shaft j5 at its tip.

[0087] The lever body q1 is inserted into shaft holes h3 provided in the left and right side plates d1 of the back support D. An operating end q11 is provided on the outside, i.e., the tip side, of the lever body q1, which is gripped by the user and to which the user's rotational operating force is applied.

[0088] The arm portion q2 is attached to the base end of the lever body q1. The arm portion q2 extends forward in a direction intersecting the lever body q1. The front part of the arm portion q2 is provided with an elongated shaft holding hole q21 that can hold the engaging shaft j5 so that it can move in the vertical direction. The shaft holding hole q21 is elongated in the front-rear direction. The reason why the shaft holding hole q21 is formed as an elongated hole is that, as the shape of the engaging portion h2 is partially arc-shaped, the engaging shaft j5 also moves back and forth along with the vertical movement within the engaging portion h2.

[0089] <Regarding the angle of the first compression reaction spring K in the reaction force adjustment mechanism G> The reaction force adjustment mechanism G described above always maintains the same angle when the back support D is unloaded, i.e., in its normal position (L).

[0090] More specifically, the reaction force adjustment mechanism G is configured such that, when the back support D is unloaded (when the backrest and back support D are not bearing the weight of the seated person), the axis line f of the first compression reaction spring K extends at the same angle with respect to the horizontal line in any of the five different reaction force setting states: the first reaction force setting state S1, the second reaction force setting state S2, the third reaction force setting state S3, the fourth reaction force setting state S4, and the fifth reaction force setting state S5.

[0091] <Regarding the operation of the reaction force adjustment mechanism G> Next, the operation of the reaction force adjustment mechanism G shown in this embodiment will be described.

[0092] The back support D maintains its normal position (L) under no-load conditions, i.e., when no load is applied to the back support D by the seated person, due to the biasing forces of the first compression reaction spring K and the second compression reaction spring M.

[0093] In this embodiment, the first compression reaction spring K uses the main shaft j1 held by the back support D as a base and, with a weak biasing force that does not cause rattling between the front shaft j4 and the intermediate member N, presses the upper part of the intermediate member N forward via the front shaft j4 and also presses the connecting member P forward.

[0094] On the other hand, the second compression reaction spring M plays the main role in holding the back support D in its normal position (L). The second compression reaction spring M uses the support shaft j2 held by the back support D as a base and presses the spring receiving shaft j3, which is provided at the lower end of the back support D, backward. The portion of the back support D near the spring receiving shaft j3 abuts against the positioning portion b14 provided on the inner surface of the inclined bottom wall portion b12 of the support base B, thereby positioning the back support D in its normal position (L).

[0095] The user can move the engagement shaft j5, which is interposed between the connecting member P and the back support D and held in place at a predetermined position on the engagement part h2 by a stopper mechanism E, in the vertical direction by operating the reaction force adjustment lever Q. In this embodiment, the stopper mechanism E using a ring spring C allows the engagement shaft j5 to be moved to five different locations in the vertical direction.

[0096] More specifically, the user can adjust the engagement shaft j5 to one of the following positions within the elongated engagement portion h2 by operating the reaction force adjustment lever Q: the uppermost position, the second position from the top, the third position from the top (third position from the bottom), the fourth position from the top (second position from the bottom), or the fifth position from the top (lowest position).

[0097] Figures 9 and 10 show an configuration in which the engaging shaft j5 is positioned at the uppermost location set in the elongated engaging portion h2 (first reaction force setting state S1).

[0098] Figures 11 and 12 show an configuration in which the engaging shaft j5 is positioned in the second position from the top, set in the elongated engaging portion h2 (second reaction force setting state S2).

[0099] Figures 13 and 14 show an configuration in which the engaging shaft j5 is positioned in the third position from the top (third position from the bottom) of the elongated engaging portion h2 (third reaction force setting state S3).

[0100] Figures 15 and 16 show an configuration in which the engagement shaft j5 is positioned in the fourth position from the top (second position from the bottom) of the elongated engagement portion h2 (fourth reaction force setting state S4).

[0101] Figures 17 and 18 show an configuration in which the engagement shaft j5 is positioned at the fifth position from the top (the lowest position) in the elongated engagement portion h2 (fifth reaction force setting state S5).

[0102] When the user's weight is applied to the backrest, and the back support D tilts backward from its normal position (L), the back support D in the normal position (L) rotates around the main axis j1.

[0103] The spring bearing shaft j3 of the back support D, which is located below the main shaft j1, moves forward, compressing the second compression reaction spring M.

[0104] The engaging shaft j5, which is held by the back support D above the main shaft j1, moves backward, causing the connecting member P connected to the engaging shaft j5 to move backward. Since the connecting member P holds the front shaft j4, the first compression reaction spring K is compressed between the front shaft j4 and the main shaft j1 as the connecting member P moves backward. The intermediate member N connected to the front shaft j4 rotates around the support shaft j2, changing its posture to one that is tilted backward from its initial position.

[0105] The rearward movement of the front axis j4 is caused by the rotation of the back support D around its main axis j1, which pulls the front axis j4, the point of application of force, backward via the engaging axis j5 and connecting member P. The greater the distance between the main axis j1, which acts as the fulcrum, and the engaging axis j5, which acts as the point of force application, the weaker the reaction force against the backward tilting movement of the back support D becomes, based on the lever mechanism.

[0106] The reaction force adjustment mechanism G is set such that the distance between the main shaft j1 and the engaging shaft j5 decreases in the order of the first reaction force setting state S1 shown in Figures 9 and 10, the second reaction force setting state S2 shown in Figures 11 and 12, the third reaction force setting state S3 shown in Figures 13 and 14, the fourth reaction force setting state S4 shown in Figures 15 and 16, and the fifth reaction force setting state S5 shown in Figures 17 and 18. As a result, the reaction force against the backward tilting movement of the back support D increases as the reaction force adjustment mechanism G transitions from the first reaction force setting state S1 to the fifth reaction force setting state S5.

[0107] Furthermore, the limit position (final tilt position) of the reclined posture (J) on the back support D is the same regardless of whether the first, second, third, fourth, or fifth reaction force setting states S1, S2, S3, S4, or S5 are used.

[0108] In this embodiment, the reaction force can be increased or decreased by moving the engagement shaft j5, which is a different shaft from the shafts supporting the first compression reaction spring K and the second compression reaction spring M (main shaft j1, front shaft j4, support shaft j2, spring receiving shaft j3), within the engagement portion h2 of the back support D. Therefore, the five stages of reaction force settings S1, S2, S3, S4, and S5 for the backward tilting movement of the back support D can be set with extremely light operation compared to conventional methods.

[0109] In the embodiment described above, the reaction force adjustment mechanism G includes a connecting member P that connects the intermediate member N and the back support D, and the reaction force of the first compression reaction spring K is changed by repositioning the engagement shaft j5 interposed between the connecting member P and the back support D in a direction that intersects the axis f of the first compression reaction spring K.

[0110] Therefore, with the chair of this embodiment, the reaction force can be set without tilting the first compression reaction spring K to change its reaction force characteristics, and moreover, by moving the engagement axis j5, which is a different axis from the axis (main axis j1) that supports the first compression reaction spring K, relative to the back support D.

[0111] Therefore, the chair of this embodiment offers excellent design flexibility, allowing for the setting of the reaction force against the backward tilting movement of the back support D with extremely light operation compared to conventional designs.

[0112] In the embodiment described above, the reaction force transmission mechanism H generates a reaction force in the first compression reaction spring K by pulling the front end of the first compression reaction spring K backward in conjunction with the backward tilting movement of the back support D, and transmits that reaction force to the back support D.

[0113] Therefore, with the chair of this embodiment, the first compression reaction spring K can be suitably positioned in an area of ​​the support base B that tends to become dead space. In other words, the chair of this embodiment offers excellent design flexibility, allowing the first compression reaction spring K to be suitably positioned within the support base B. As described above, the chair according to this embodiment comprises a support base B, a back support D rotatably supported with respect to the support base B, and a first compression reaction spring K, which is a compression reaction spring that is compressed in conjunction with the backward tilting movement of the back support D, thereby generating a reaction force in the upright direction, i.e., the normal posture (L) direction, of the back support D.

[0114] The first compression reaction spring K has its front end supported by the front structure so as to be movable relative to the support base B, and its rear end supported by the rear structure to the support base B.

[0115] A reaction force adjustment mechanism G is provided to vary the reaction force of the first compression reaction spring K in response to the backward tilting movement of the back support D. The reaction force adjustment mechanism G includes a connecting member P that is connected to the support base B by a front structure and to the back support D by an engagement structure. By compressing the first compression reaction spring K in accordance with the rotational movement of the back support D, a reaction force is generated on the back support D in the direction of the normal posture (L). The magnitude of the reaction force is changed by changing the position of the connecting member P in a direction that intersects the axis f of the compression reaction spring.

[0116] Therefore, this embodiment provides a chair that allows for a suitable setting of the reaction force against the backward tilting movement of the back support D.

[0117] The front structure includes an intermediate member N, which is a rotating member having one end rotatably supported by a support base B and the other end. The front structure is rotatably engaged with the front end of the first compression reaction spring K and the front end of the connecting member P via a front axis j4, which is the axis, on the other end of the intermediate member N excluding the one end.

[0118] Therefore, a configuration in which the front end of the first compression reaction spring K is supported so as to be movable relative to the support base B is preferably realized.

[0119] The rear structure consists of a first compression reaction spring K whose rear end is rotatably supported on a support base B via a main shaft j1, which is the axis.

[0120] Therefore, the first compression reaction spring K is suitably supported with respect to the support base B.

[0121] The engagement structure allows the position of the connection between the rear end of the connecting member P and the back support D, that is, the position where the engagement axis j5 and the engagement portion h2 engage, to be changed to two or more different positions at a distance from the rotation center of the back support D.

[0122] Therefore, the engagement structure is configured to be less susceptible to the biasing force of the first compression reaction spring K.

[0123] The rear end of the connecting member P is an engagement pin, or engagement shaft j5, and the connecting portion of the back support D is an engagement guide, or elongated hole-shaped engagement portion h2, which extends in an arc shape with the front end of the connecting member P as its center point, and the engagement shaft j5 engages with the engagement portion h2 in a manner that can be changed to two or more different positions.

[0124] Therefore, the engagement structure has a suitable configuration for engaging the engagement shaft j5 and the engagement portion h2.

[0125] The reaction force adjustment mechanism G is configured such that, when the back support D is unloaded, the axis line f of the first compression reaction spring K extends at the same angle with respect to the horizontal line, even if the position of the connecting member P is changed.

[0126] Therefore, the reaction force characteristics of the first compression reaction spring K remain unchanged in all of the multiple reaction force setting states S1, S2, S3, S4, and S5, namely the first, second, third, fourth, and fifth.

[0127] The device has an operating mechanism that changes the position of the connection between the rear end of the connecting member P and the back support D in a direction intersecting the axis line f by transmitting an operating force from the user.

[0128] Therefore, the position of the connection between the rear end of the connecting member P and the back support D can be changed by the operating means to a direction intersecting the axis line f by transmitting an operating force from the user.

[0129] A second compression reaction spring M is interposed between the back support D and the support base B, separate from the first compression reaction spring K, and is another reaction spring that generates a reaction force against the backward tilting movement of the back support D.

[0130] Therefore, the second compression reaction spring M plays the main role in biasing the back support D in the normal position (L), and the design offers excellent freedom in setting the biasing force of the first compression reaction spring K to zero or very weak when the back support D is in the normal position (L).

[0131] However, the present invention is not limited to the embodiments described in detail above.

[0132] In the embodiment described above, a second compression reaction spring (second compression reaction spring) was interposed between the back support and the support base, in addition to the first compression reaction spring, to generate a reaction force against the backward tilting movement of the back support. However, the embodiment may not include any other reaction spring.

[0133] The operating means only needs to be capable of changing the position of the connection between the rear end of the connecting member and the back support in a direction intersecting the axis by transmitting an operating force from the user, and its specific configuration can be anything.

[0134] For example, the operating means Q may be configured such that, as shown in Figure 19, the arm portion q2 is moved by moving a wire wy connected to the operating end (not shown) back and forth, thereby moving the engagement pin (engagement shaft j5), which is the connection part between the rear end of the connecting member P and the back support D.

[0135] Various configurations can be set for supporting the front end of the compression reaction spring without departing from the spirit of the present invention.

[0136] As shown in Figure 20, for example, the front end of a first compression reaction spring K, which is a compression reaction spring, may be rotatably and slidably supported on a front shaft j4, which is an axis, relative to the support base B. In other words, the example shown in Figure 20 does not have an intermediate member pivotally supported on the support shaft. Instead, slits b21 extending in the front-rear direction are provided on the left and right side walls b2 of the support base B, and the front shaft j4 is directly or indirectly engaged with these slits b21 in a manner that allows it to move in the front-rear direction.

[0137] As shown in Figure 21, for example, the front end of the first compression reaction spring K, which is a compression reaction spring, may directly or indirectly bias the vertically intermediate portion of the intermediate member N. In other words, the example shown in Figure 21 is configured such that the front end of the first compression reaction spring K is connected to the vertically intermediate portion of the intermediate member N via the shaft j6. Even with such a configuration, the intended purpose can be achieved.

[0138] As shown in Figure 22, the front structure connecting the first compression reaction spring Kx, which is a compression reaction spring, and the support base B has a slit-shaped slide guide b22 provided on the support base B, a slider sd that is movable guided by the slide guide b22, and a front shaft j4 held by the slider sd. The slider sd may be supported at the front end of the first compression reaction spring Kx via the front shaft j4 and engaged with the slider sd via the front shaft j4 of the connecting member P.

[0139] In such a configuration, it is desirable that, when the back support D is unloaded, the slider sd contacts a part of the support base B or a locking member attached to the support base B.

[0140] Furthermore, the rear structure connecting the compression reaction spring K and the support base B is preferably such that the rear end of the compression reaction spring Kx is fixed immovably to the support base B, and the direction in which the slide guide b22 extends may coincide with the direction of the axis line f of the compression reaction spring Kx.

[0141] Even with this configuration, it is possible to achieve the intended purpose.

[0142] Furthermore, the other reaction springs are not limited to compression springs; tension springs may also be used.

[0143] The compression reaction spring may be set so as not to bias the main shaft and the front shaft away from each other when the back support is unloaded. In other words, the compression reaction spring may be set so as to be at its so-called natural length, fully extended in the axial direction, when the back support is unloaded.

[0144] With this configuration, the engagement pin (engagement shaft) can be moved up and down with extremely light operation. In other words, since there is no need to move the engagement pin (engagement shaft) up and down against the biasing force of the compression reaction spring, the increase or decrease of the reaction force in response to the backward tilting movement of the back support can be set with light operation.

[0145] Furthermore, if the compression reaction spring is set so as not to bias the main shaft and the front shaft away from each other when the back support is unloaded, it is desirable to provide a biasing mechanism that biases the front shaft away from the main shaft when the back support is unloaded, in order to suppress rattling between the compression reaction spring and the front shaft and rattling between the intermediate member and the front shaft when the back support is unloaded.

[0146] The seat may be linked to the tilting of the back support. If the seat is linked to the tilting of the back support, it is desirable that the seat be rotatably connected to the back support as well.

[0147] The intermediate member may be configured to contact a part of the support base or a locking member attached to the support base when the back support is unloaded. With this configuration, the intermediate member is maintained in an appropriate position when the support base is unloaded.

[0148] The engagement structure, which includes an engagement pin (engagement shaft), engagement hole, and stopper mechanism that constitute the reaction force adjustment mechanism, is not limited to being provided on the rear side of the connecting member, but may also be provided on the front side of the connecting member.

[0149] Furthermore, the specific configuration of each part is not limited to the above embodiments, and various modifications are possible without departing from the spirit of the present invention. [Explanation of symbols]

[0150] A...legs B...Support base D...back support E...moderation mechanism G... Reaction force adjustment mechanism H...Reaction force transmission mechanism K...First compression reaction spring (compression reaction spring) M... Second compression reaction spring (other reaction springs) N...Intermediate member P...Connecting component Q... Reaction force adjustment lever j5…Engagement axis (engagement pin)

Claims

1. A chair comprising a support base, a back support rotatably supported with respect to the support base, and a compression spring that, when compressed in conjunction with the backward tilting movement of the back support, generates a reaction force in the upright direction of the back support, The compression reaction spring has its front end supported by the front structure so as to be movable relative to the support base, and its rear end supported by the rear structure to the support base. A reaction force adjustment mechanism is provided to vary the reaction force of the compression reaction spring in response to the backward tilting movement of the back support. The reaction force adjustment mechanism includes a connecting member that is connected to the support base by the front structure and to the back support by an engaging structure, and generates an upright reaction force on the back support by compressing the compression reaction spring in conjunction with the rotational movement of the back support. A chair that changes the magnitude of the reaction force by changing the position of the connecting member in a direction that intersects the axis of the compression reaction spring.

2. The chair according to claim 1, wherein the front structure includes a rotating member having one end rotatably supported with respect to the support base and the other end, and the front end of the compression reaction spring and the front end of the connecting member are rotatably engaged with the other end of the rotating member excluding the one end.

3. The chair according to claim 2, wherein when the back support is unloaded, the rotating member abuts against a part of the support base or a locking member attached to the support base.

4. The front structure includes a slide guide provided on the support base and a slider that is movable guided by the slide guide. The chair according to claim 1, wherein the front end of the compression reaction spring and the front end of the connecting member are engaged with the slider.

5. The chair according to claim 4, wherein, when the back support is unloaded, the slider abuts against a part of the support base or a locking member attached to the support base.

6. The chair according to claim 1, wherein the rear structure rotatably supports the rear end of the compression reaction spring on the support base.

7. The aforementioned rear structure is such that the rear end of the compression reaction spring is fixed immovably to the support base. The chair according to claim 4 or 5, wherein the direction in which the slide guide extends coincides with the direction of the axis of the compression reaction spring.

8. The chair according to claim 1, wherein the engagement structure allows the position of the connection between the rear end of the connecting member and the back support to be changed to two or more different positions at a distance from the rotation center of the back support.

9. The rear end of the connecting member is an engagement pin, and the connecting portion of the back support is an engagement guide that extends in an arc shape from the front end of the connecting member. The chair according to claim 8, wherein the engaging pin engages with the engaging guide in a manner that can be changed to two or more different positions.

10. The chair according to claim 8 or 9, wherein the reaction force adjustment mechanism is configured such that, when the back support is unloaded, the axis of the compression reaction spring extends at the same angle with respect to the horizontal line even when the position of the connecting member is changed.

11. The chair according to claim 3, wherein, when the back support is unloaded, the reaction force of the compression reaction spring does not exert on the connecting member.

12. The chair according to claim 8, further comprising an operating means for changing the position of the connection between the rear end of the connecting member and the back support in a direction intersecting the axis by transmitting an operating force from the user.

13. The chair according to claim 1, wherein another reaction spring is interposed between the back support and the support base, separately from the compression reaction spring, to generate a reaction force against the backward tilting movement of the back support.

14. When the back support is unloaded, the compression reaction spring reaches its natural length. The chair according to claim 13, wherein the other reaction spring biases the back support away from the support base.

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