Chair and seat support mechanism

Abstract

To provide a chair in which the seated person can perceive a comfortable sitting feeling even if sitting for a long time, and furthermore a high work efficiency can stably be maintained, a chair according to the present invention includes a support mechanism 2 interposed between a leg 1 and a seat 3, wherein the support mechanism 2 includes: a seat inclining mechanism Q as a seat inclining function configured to downwardly incline a tip side in an operation direction of the seat 3 when the seat 3 operates from a predetermined reference position (S), and further includes: a return-force generation mechanism configured to generate, in accordance with an amount of movement, a return force in a direction of returning the seat 3 having moved from a reference position (S) in a front-rear or left-right direction, to the reference position (S).

Claims

1. A chair comprising: a leg erected on a floor surface; a seat arranged above the leg; a rotation support mechanism configured to rotatably support the seat in a horizontal direction relative to the leg; and a support mechanism interposed between the leg and the seat, the support mechanism being configured to operatively support the seat by relative operation between a guide surface and a follower, and the support mechanism including the guide surface formed along a predetermined trajectory along which the seat is operated in a front-rear direction and a right-left direction, and the follower configured to perform a sliding operation following the guide surface, the support mechanism comprises; a seat inclining function configured to downwardly incline a tip side towards an operation direction of the seat when the seat operates from a predetermined reference position, and further comprises: a return-force generation mechanism configured to generate, in accordance with an amount of movement, a return force in a direction of returning the seat to the reference position when the seat operates in a movement direction from the reference position, wherein the guide surface is integrally formed, and the support mechanism has a plurality of the followers that can operate in the front-rear direction and the right-left direction along the guide surface so that the support mechanism and the rotation support mechanism are configured integrally.

2. The chair according to claim 1, wherein the leg includes a lifting and lowering mechanism, the seat is arranged above the lifting and lowering mechanism, and the support mechanism is interposed between the lifting and lowering mechanism and the seat.

3. The chair according to claim 1, wherein the return-force generation mechanism is a center-of-gravity movement mechanism configured to elevate a center of gravity of the seat in accordance with an operation of the seat from the reference position.

4. The chair according to claim 1, wherein the guide surface is set so that there are always, at least one follower ascending and at least one another follower descending, during the operation of the seat.

5. The chair according to claim 1, wherein the guide surface has a substantially conical shape.

6. The chair according to claim 1, wherein the follower contacts the guide surface at three or more locations.

7. The chair according to claim 1, wherein the support mechanism is configured to operatively support independently in each of the front-rear direction and the left-right direction along a predetermined trajectory.

8. A chair comprising: a leg erected on a floor surface; a seat arranged above the leg; and a support mechanism interposed between the leg and the seat, the support mechanism being configured to operatively support the seat by relative operation between a guide surface and a follower, and the support mechanism including the guide surface formed along a predetermined trajectory along which the seat is operated in a front-rear direction and a right-left direction, and the follower configured to perform a sliding operation following the guide surface, the support mechanism comprises; a seat inclining function configured to downwardly incline a tip side towards an operation direction of the seat when the seat operates from a predetermined reference position, and further comprises: a return-force generation mechanism configured to generate, in accordance with an amount of movement, a return force in a direction of returning the seat to the reference position when the seat operates in a movement direction from the reference position, wherein the support mechanism is configured to operatively support independently in each of the front-rear direction and the left-right direction along a predetermined trajectory, wherein an operation angle and an operation distance of the seat in the front-rear direction are set so as to be larger than those in the left-right direction.

9. The chair according to claim 8, comprising a rotation support mechanism configured to rotatably support the seat in a horizontal direction relative to the leg.

10. The chair according to claim 8, wherein an operation angle of the seat in a front direction is set to be larger than that in a rear direction.

11. The chair according to claim 8, wherein the guide surface has an upward or downward curved shape.

12. The chair according to claim 8, wherein the leg includes a lifting and lowering mechanism, the seat is arranged above the lifting and lowering mechanism, and the support mechanism is interposed between the lifting and lowering mechanism and the seat.

13. The chair according to claim 8, wherein the return-force generation mechanism is a center-of-gravity movement mechanism configured to elevate a center of gravity of the seat in accordance with an operation of the seat from the reference position.

14. A chair comprising: a leg erected on a floor surface; a seat arranged above the leg; and a support mechanism interposed between the leg and the seat, the support mechanism being configured to operatively support the seat by relative operation between a guide surface and a follower, and the support mechanism including the guide surface formed along a predetermined trajectory along which the seat is operated in a front-rear direction and a right-left direction, and the follower configured to perform a sliding operation following the guide surface, the support mechanism comprises; a seat inclining function configured to downwardly incline a tip side towards an operation direction of the seat when the seat operates from a predetermined reference position, and further comprises: a return-force generation mechanism configured to generate, in accordance with an amount of movement, a return force in a direction of returning the seat to the reference position when the seat operates in a movement direction from the reference position, wherein the support mechanism is configured to operatively support independently in each of the front-rear direction and the left-right direction along a predetermined trajectory, wherein the support mechanism includes a front-rear support unit configured to operatively support the seat in the front-rear direction and a left-right support unit configured separately from the front-rear support unit and configured to operatively support the seat in the left-right direction, and the return-force generation mechanism includes a front-rear return unit configured to generate a return force in the front-rear direction and a left-right return unit configured separately from the front-rear return unit and configured to generate a return force in the left-right direction.

15. The chair according to claim 14, wherein the front-rear support unit is arranged above the left-right support unit.

16. The chair according to claim 14, wherein the leg includes a lifting and lowering mechanism, the seat is arranged above the lifting and lowering mechanism, and the support mechanism is interposed between the lifting and lowering mechanism and the seat.

17. The chair according to claim 14, wherein the return-force generation mechanism is a center-of-gravity movement mechanism configured to elevate a center of gravity of the seat in accordance with an operation of the seat from the reference position.

18. A chair comprising: a leg erected on a floor surface; a seat arranged above the leg; and a support mechanism interposed between the leg and the seat, the support mechanism being configured to operatively support the seat by relative operation between a guide surface and a follower, and the support mechanism including the guide surface formed along a predetermined trajectory along which the seat is operated in a front-rear direction and a right-left direction, and the follower configured to perform a sliding operation following the guide surface, the support mechanism comprises; a seat inclining function configured to downwardly incline a tip side towards an operation direction of the seat when the seat operates from a predetermined reference position, and further comprises: a return-force generation mechanism configured to generate, in accordance with an amount of movement, a return force in a direction of returning the seat to the reference position when the seat operates in a movement direction from the reference position, wherein the support mechanism includes a slowing portion configured to slow an operation of the follower in accordance with its closeness to an operation end of the followers.

19. The chair according to claim 18, wherein the leg includes a lifting and lowering mechanism, the seat is arranged above the lifting and lowering mechanism, and the support mechanism is interposed between the lifting and lowering mechanism and the seat.

20. A chair comprising: a leg erected on a floor surface; a seat arranged above the leg; and a support mechanism interposed between the leg and the seat, the support mechanism being configured to operatively support the seat by relative operation between a guide surface and a follower, and the support mechanism including the guide surface formed along a predetermined trajectory along which the seat is operated in a front-rear direction and a right-left direction, and the follower configured to perform a sliding operation following the guide surface, the support mechanism comprises; a seat inclining function configured to downwardly incline a tip side towards an operation direction of the seat when the seat operates from a predetermined reference position, and further comprises: a return-force generation mechanism configured to generate, in accordance with an amount of movement, a return force in a direction of returning the seat to the reference position when the seat operates in a movement direction from the reference position, wherein the support mechanism includes a shockless unit configured to avoid or absorb a shock caused by a collision between an end of the guide surfaces and the follower at the operation end.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is an appearance diagram according to a first embodiment of the present invention.

(2) FIG. 2 is a front view according thereto.

(3) FIG. 3 is a side view according thereto.

(4) FIG. 4 is a perspective view of main parts according thereto.

(5) FIG. 5 is an exploded perspective view according thereof.

(6) FIG. 6 is an exploded perspective view according thereof.

(7) FIG. 7 is an operation explanatory diagram according thereto.

(8) FIG. 8 is an operation explanatory diagram according thereto.

(9) FIG. 9 is an explanatory diagram of an effect according thereto.

(10) FIG. 10 is an explanatory diagram of an effect according thereto.

(11) FIG. 11 is an explanatory diagram according to a modification of the first embodiment.

(12) FIG. 12 is a schematic plane cross-sectional view according to another modification thereof.

(13) FIG. 13A and FIG. 13B are explanatory diagram according to the other modification thereof.

(14) FIG. 14 is a front view according to a second embodiment of the present invention.

(15) FIG. 15 is an exploded perspective view according thereto.

(16) FIG. 16 is an exploded perspective view according thereto.

(17) FIG. 17 is an operation explanatory diagram according thereto.

(18) FIG. 18 is a front view according to a modification according thereto.

MODE FOR CARRYING OUT THE INVENTION

(19) Each of embodiments of the present invention will be described below with reference to the drawings.

First Embodiment

(20) A chair according to a first embodiment of the present invention is referred to as an office rotating chair that can suitably be used in an office or at home.

(21) As illustrated in FIG. 1 to FIG. 8, the chair mainly includes: a leg 1 erected on a floor surface, a seat 3 arranged above the leg 1, and a backrest 4.

(22) The leg 1 includes: a leg vane 11 formed radially in planar view; a caster 12 attached to a bottom side of the leg vane 11 and rollably contacting the floor surface; a leg supporting post 13 erected on a center of the leg vane 11; a gas spring 14 being a lifting/lowering mechanism mounted within the leg supporting post 13 and configured to support the seat 3 in a lifting/lowering manner, a rotation support mechanism 16 configured to support, in the vicinity of an upper end of the leg supporting post 13, the seat 3 to permit horizontal rotation by allowing a rod of the gas spring 14 to relatively rotate with respect to the leg supporting post 13; and an operation lever 15 configured to adjust a vertical position of the seat 3 by pressing a push button 17 arranged at an upper end of the gas spring 14 to extend and shrink the gas spring 14.

(23) In the present embodiment, the seat 3 is constructed mainly of a seat main body 30 of a plate shape formed integrally with the backrest 4, where a top surface of the seat main body 30 is a seat surface 3a, and a seat receiver 31 for supporting the seat 3 from below is attached on a bottom surface side of the seat main body 30.

(24) Here, in a chair according to the present embodiment, a support mechanism 2 interposed between the leg 1 and the seat 3, includes a seat inclining mechanism Q being a seat inclining function configured to downwardly incline a tip side in an operating direction of the seat 3 in accordance with movement of the seat 3 when the seat 3 operates from the predetermined reference position (S), and further includes a return-force generation mechanism configured to generate, in accordance with an amount of movement, a return force in a direction of returning the seat 3 having moved from a reference position (S) in the front-rear or left-right direction, to the reference position (S).

(25) In order to realize the above-described behavior of the seat 3 with the support mechanism 2 alone, as illustrated in FIG. 1 to FIG. 6, the support mechanism 2 in the present embodiment includes guide surfaces 23a, 23b, 25a, and 25b interposed between the leg 1 and the seat 3 and formed along a predetermined trajectory for moving the seat 3 in the front-rear direction and the left-right direction and followers 24a, 24b, 26a, and 26b configured to perform a slide operation following the guide surfaces 23a, 23b, 25a, and 25b, and operatively supports the seat 3 by a relative operation of the guide surfaces 23a, 23b, 25a, and 25b and the followers 24a, 24b, 26a, and 26b. Further, the support mechanism 2 is configured to draw a trajectory along which the tip side in a movement direction of the seat 3 is downwardly inclined when the seat 3 operates from the predetermined reference position (S), and the support mechanism 2 further includes a return-force generation mechanism configured to generate, in accordance with the amount of movement, the return force in the direction of returning the supporting locations to the seat 3 having moved from the reference position (S) in the front-rear or left-right direction, to the reference position (S). In addition, the load from the above of the seated person (the load due to the movement of the center of gravity) is input to the seat 3, the load from the upper side of the seated person (the load due to the movement of the center of gravity) is input to the seat 3; and the seat 3 is guided so as to increase the moving distance in the traveling direction while increasing the action angle with the tip side in the moving direction downward.

(26) The support mechanism 2 is configured from an upper end portion of the leg 1 to a lower end portion of the seat receiver 31. Specifically, the support mechanism 2 is configured by the upper end portion of the leg 1, the lower end portion of the seat receiver 31, and a support housing 20 interposed between the upper end portion of the leg 1 and the lower end portion of the seat receiver 31. In the support mechanism 2, a pair of left-right support units 21 in the front-rear direction configured to operatively support the seat 3 in the left-right direction is configured over the upper end portion of the leg 1 and a lower half region of the support housing 20, and a pair of front-rear support units 22 in the left-right direction configured to operatively support the seat 3 in the front-rear direction is configured over the lower end portion of the seat receiver 31 and an upper half region of the support housing 20. That is, the left-right support units 21 and the front-rear support units 22 overlap at an overlapping position in planar view are configured respectively independently as a separate body. In the present embodiment, the front-rear support units 22 directly supports the seat 3 configured integrally with the backrest 4, and thus, in the present embodiment, a configuration in which the backrest 4 is indirectly attached to the front-rear support unit 22 is adopted, and needless to say, a configuration in which the backrest 4 is directly attached in a region of the upper half portion of the support housing 20 shall not be precluded.

(27) The left-right support unit 21 is for supporting the seat 3 so that the seat 3 is inclinable at 3.4° in the left-right direction, and includes a left-right guide hole 23 formed in the lower half region of the support housing 20 and a left-right support axis 24 formed at the upper end of the leg 1, where the both ends of the left-right support axis 24 are inserted in the left-right guide hole 23. At both ends in the front and rear direction of the left-right support axis 24, a left follower 24a and a right follower 24b configured to operate smoothly within the left-right guide hole 23 are arranged. Further, surfaces in contact with the left follower 24a and the right follower 24b in the left-right guide hole 23 correspond to a left guide surface 23a and a right guide surface 23b. The left guide surface 23a and the right guide surface 23b form an upward curved shape to run along a previously set predetermined trajectory. That is, in the present embodiment, the left support structure is configured by the left guide surface 23a and the left follower 24a. Further, the right support structure is configured by the right guide surface 23b and the right follower 24b.

(28) In the present embodiment, the upward curved shape is divided into first regions 23a1 and 23b1 designated as a constant operation range including the reference position (S) and second regions 23a2 and 23b2 designated as a range reaching a vicinity of an operation end beyond the operation range. It is so set that in the first regions 23a1 and 23b1, through a collaboration with the followers 24a and 24b, while a center-of-gravity movement in a height direction of the seat 3 is suppressed (accordingly, while a return force to the reference position (S) is suppressed) and while an inclination angle of the seat 3 is suppressed, the seat 3 is guided in a direction away from the reference position (S), and when the second regions 23a2 and 23b2 are reached, through a collaboration with the followers 24a and 24b, while the center-of-gravity movement in the height direction of the seat 3 is increased (accordingly, while a return force to the reference position (S) is increased) and while the inclination angle of the seat 3 is increased, the seat 3 is guided in the direction away from the reference position (S). That is, in the present embodiment, the slowing portion is so configured that a mobility of the seat 3 is gradually slowed down by an increase in return force, as the followers 24a and 24b follow from the first regions 23a1 and 23b1 to the second regions 23a2 and 23b2. In other words, the slowing portion includes the first regions 23a1 and 23b1 and the second regions 23a2 and 23b2. The first regions 23a1 and 23b1 and the second regions 23a2 and 23b2 are continuous, and thus, it is difficult to clearly indicate a boundary position; however, a position at which a center-of-gravity movement rate in the height direction of the seat 3 is changed from low to high may be considered as the boundary position.

(29) It is noted that, in the present embodiment, at an operation end located at a left end of the left-side guide hole 23 and an operation end located at a right end of the right-side guide hole 23, when the seat 3 is changed steeply in a lifted direction while keeping the inclination angle of the seat constant, a shockless unit R is configured which ensures that the left follower 24a and the right follower 24b make practically little or no contact with both left and right end surfaces of the left-right guide holes 23. As a result, a collision between the left follower 24a and the right follower 24b; and the end surface of the left-right guide holes 23 at the operation end can be avoided. It is noted that, the left-right guide holes 23 may be arranged continuously and integrally.

(30) The front-rear support unit 22 is arranged above the left-right support unit 21 and is positioned closer to the seated person to more easily react to the movement of the seated person. The front-rear support unit 22 is configured to support the seat 3 so that the seat 3 can be inclined at 8° forward and at 10° rearward and includes front-rear guide holes 25 formed in the upper half region of the support housing 20 and a front-rear support axis 26 formed at the lower end of the seat receiver 31, where the both ends are inserted in the front-rear guide holes 25. The front follower 26a and the rear follower 26b configured to move smoothly within the front-rear guide holes 25, are arranged at both left and right ends of the front-rear support axis 26. Surfaces in contact with the front follower 26a and the rear follower 26b in the front-rear guide holes 25 correspond to the front guide surface 25a and the rear guide surface 25b. The front guide surface 25a and the rear guide surface 25b form an upward curved shape to run along a previously set predetermined trajectory. That is, in the present embodiment, the front support structure is configured by the front guide surface 25a and the front follower 26a. Further, the rear support structure is configured by the rear guide surface 25b and the rear follower 26b.

(31) In the present embodiment, the upward curved shape is divided into first regions 25a1 and 25b1 designated as a constant operation range including the reference position (S) and second regions 25a2 and 25b2 designated as a range reaching a vicinity of an operation end beyond the operation range. It is so set that in the first regions 25a1 and 25b1, through a collaboration with the followers 26a and 26b, while a center-of-gravity movement in a height direction of the seat 3 is suppressed (accordingly, while a return force to the reference position (S) is suppressed) and while an inclination angle of the seat 3 is suppressed, the seat 3 is guided in a direction away from the reference position (S) and when the second regions 25a2 and 25b2 are reached, through a collaboration with the followers 26a and 26b, while the height direction of the seat 3 is increased (accordingly, while a return force to the reference position (S) is increased) and while the inclination angle of the seat 3 is increased, the seat 3 is guided in the direction away from the reference position (S). That is, in the present embodiment, the slowing portion is so configured that a mobility of the seat 3 is gradually slowed down by an increase in return force, as the followers 26a and 26b follow from the first regions 25a1 and 25b1 to the second regions 25a2 and 25b2. In other words, the slowing portion includes the first regions 25a1 and 25b1 and the second regions 25a2 and 25b2. The first regions 25a1 and 25b1 and the second regions 25a2 and 25b2 are continuous, and thus, it is difficult to clearly indicate a boundary position; however, a position at which a center-of-gravity movement rate in the height direction of the seat 3 is changed from low to high may be considered as the boundary position.

(32) It is noted that, in the present embodiment, at the front-rear operation ends of the front-rear guide holes 25, when the center of gravity G of the seat 3 is changed steeply in a lifted direction while keeping the inclination angle of the seat constant, the shockless unit R is configured which avoid or absorbs a shock so that the front follower 26a and the rear follower 26b make no contact with front-rear both end surfaces of the front-rear guide holes 25. As a result, a collision between the front follower 26a and the rear follower 26b; and the end surface of the front-rear guide holes 25 at the operation end can be avoided. It is noted that, the front-rear guide holes 25 may be arranged continuously and integrally.

(33) To specifically describe a front-rear operation of the seat 3, when the seat 3 at the reference position (S) swings forward, the rear follower 26b follows the upwardly inclined first region 25b1, and at the same time, the front follower 26a follows the downwardly inclined first region 25a1. As a result, little return force is exerted on the forward operation of the seat 3, in the vicinity of the reference position (S). Afterward, when the seat 3 operates further forward from the reference position (S), each of the front and rear followers 26a, 26b approaches the upwardly inclined second regions 25a2 and 25b2, the return force increases as a degree of elevation of a center of gravity G of the seat 3 increases. Further, in the vicinity of the operation end, when the center of gravity G of the seat 3 is changed steeply in a lifted direction while keeping the inclination angle of the seat 3 constant, the shockless unit R is formed. In other words, the shockless unit R is for avoiding a shock caused by a collision between members.

(34) Further, when the seat 3 at the reference position (S) swings rearward, each of the rear follower 26b and the front follower 26a follows the upwardly inclined first regions 25a1 and 25b1, and upon further swinging, the rear follower 26b and the front follower 26a enter the second regions 25a2 and 25b2 configured with a larger inclination degree. Afterward, when the center of gravity G of the seat 3 is changed steeply in a lifted direction while keeping the inclination angle of the seat constant, the shockless unit R is formed.

(35) That is, in the present embodiment, an operation angle and an operation distance of the seat 3 freely operating forward, rearward, rightward, and leftward, in the front-rear direction are set so as to be larger than those in the left-right direction. More specifically, the operation angle of the seat 3 in the front-rear direction in a rear direction is set to be larger than that in a front direction.

(36) Here, in the present embodiment, in particular, as illustrated in FIG. 7 and FIG. 8, the movement of the seat surface 3a in the front, rear, right, and left direction, when the left follower 24a, the right follower 24b, the front follower 26a, and the rear follower 26b make a relative operation after following the left guide surface 23a, the right guide surface 23b, the front guide surface 25a, and the rear guide surface 25b, is configured to follow a previously set predetermined trajectory. In the present embodiment, the predetermined trajectory is formed along an operation range in which the seat 3 can incline at 8° forward, at 10° rearward, and at 3.4° in each of the left and right directions, with the reference position (S) as the center. Further, a movement dimension of the seat 3 based on the predetermined trajectory will be explained. If the seat 3 tilts forward at 8°, the seat 3 operates by 50 mm horizontally forward and by 4 mm upward. Further, if the seat 3 tilts rearward at 10°, the seat 3 operates by 50 mm horizontally rearward and by 6.5 mm upward. Further, at the operation end in the left-right direction, the seat 3 operates by 30 mm in the horizontal direction and by 1.8 mm upward from the reference position (S).

(37) FIG. 7 illustrates a behavior of the seat 3 when the seat 3 operates in the left-right direction from a predetermined reference position (S) set on the guide surfaces 23a and 23b. As illustrated in FIG. 7, the position and the shape of the left guide surface 23a and the right guide surface 23b are adjusted so that if the seat surface 3a operates rightward and leftward by the left-right support unit 21, a position of the center of gravity G of the seat 3 between the left and right supporting points, that is, between the left and right followers 24a and 24b, slightly rises from a position of the center of gravity G, when the seat 3 is at the reference position (S) illustrated by solid lines. As a result, when operating rightward and leftward, a return force in a direction of returning the seat 3 to the reference position (S) is spontaneously generated. That is, in the present embodiment, the left guide surface 23a and the right guide surface 23b are a left-right return unit configured to generate a return force in the left-right direction, of the return-force generation mechanism, and function as the center-of-gravity movement mechanism P configured to elevate the center of gravity G of the seat 3 as the seat 3 operates from the reference position (S). Additionally, in the seat surface 3a operating rightward and leftward in FIG. 7, the position and the shape of the left guide surface 23a and the right guide surface 23b are adjusted so that an amount of elevation at an operation base end side is greater than that at an operation tip side, and as a result, the operation tip side takes a descending posture. That is, in the present embodiment, the left guide surface 23a and the right guide surface 23b also function as the seat inclining mechanism Q.

(38) FIG. 8 illustrates a behavior of the seat 3 operating in the front-rear direction from a predetermined reference position (S) set on the guide surfaces 25a and 25b. As illustrated in FIG. 8, the position and the shape of the front guide surface 25a and the rear guide surface 25b are adjusted so that if the seat surface 3a operates forward and rearward by the front-rear support unit 22, the position of the center of gravity G of the seat 3 between the front and rear supporting points, that is, between the front and rear followers 26a and 26b, slightly rises from a position of the center of gravity G, when the seat 3 is at the reference position (S) illustrated by solid lines. As a result, when operating forward and rearward, a return force in a direction of returning the seat 3 to the reference position (S), is spontaneously generated. That is, in the present embodiment, the front guide surface 25a and the rear guide surface 25b are a front-rear return unit configured to generate a return force in the front-rear direction, out of the return-force generation mechanism, and function as the center-of-gravity movement mechanism P configured to elevate the center of gravity G of the seat 3 as the seat 3 operates from the reference position (S). Additionally, in the seat surface 3a operating forward and rearward in FIG. 7, the position and the shape of the front guide surface 25a and the rear guide surface 25b are adjusted so that an amount of elevation at the operation base end side is greater than that at the operation tip side, and as a result, the operation tip side takes a descending posture. That is, in the present embodiment, the front guide surface 25a and the rear guide surface 25b also function as the seat inclining mechanism Q.

(39) That is, in the present embodiment, by the left guide surface 23a, the right guide surface 23b, the front guide surface 25a, the rear guide surface 25b, and the left follower 24a, the right follower 24b, the front follower 26a, and the rear follower 26b that configure the support mechanism 2, the seat inclining mechanism Q and the center-of-gravity movement mechanism P being a return-force generation mechanism are configured.

(40) Additionally, in the present embodiment, as described above, the first regions 23a1, 23b1, 25a1, and 25b1 and the second regions 23a2, 23b2, 25a2, and 25b2 are provided, in addition to the left-right guide surfaces 23a and 23b, and the front-rear guide surfaces 25a and 25b. As a result, during the operation of the seat 3 in the vicinity of the reference position (S), each of the followers 24a, 24b, 26a, and 26b is guided into the first regions 23a1, 23b1, 25a1, and 25b1, and thus, a backswing force to the reference position (S) is only exerted to an extent hardly felt by the seated person. On the other hand, in the vicinity of the operation ends in the front, rear, right, and left, each of the followers 24a, 24b, 26a, and 26b is guided into the second regions 23a2, 23b2, 25a2, and 25b2, and thus, the backswing force is exerted strongly. As a result, in the vicinity of the reference position (S), the seated person can experience a pleasant operation of the seat 3, and even in the vicinity of the operation end, the seat 3 is guided again to a pleasant operation in the vicinity of the reference position (S) due to the strong backswing to the reference position (S), whereby a feeling of safety can be obtained.

(41) Subsequently, in FIG. 9 and FIG. 10, a behavior of the seated person, in particular, that of a lower body of the seated person, during the seat 3 inclining forward, will be described. Normally, if the seated person inclines the chair forward (or rearward) during sitting, as illustrated in FIG. 9 and FIG. 10, the seated person attempts to move by using an ankle (AN) as a main pivoting fulcrum, out of a knee (NE), the ankle (AN), and a vicinity of hip (HP). However, in a conventional chair, the pivoting fulcrum that operates the seat forward and rearward is spontaneously below the seat and in the vicinity of the seat 3, and thus, an operation allowing the seat to largely descend is performed together with the front-rear operation. Thus, actually, the vicinity of hip (HP) descends below the operation, and as a result, the seated person attempting to perform the operation described above unconsciously perceives a feeling where his/her knees (NE) are bent more than necessary.

(42) Therefore, in the chair according to the present embodiment, when the center-of-gravity movement mechanism P acts during the seat 3 inclining forward, as illustrated in FIG. 9 and FIG. 10, an operation of the seat 3 is realized which resembles an operation of lifting the vicinity of hip (HP) along an operation with the ankle (AN) being the main pivoting fulcrum. In addition, the action of the seat inclining mechanism Q effectively avoids the front end portion of the seat 3 from undesirably interfering with the vicinity of the knee (NE) of the seated person.

(43) Further, in the present embodiment, the operation of the seat 3 in the left-right direction may conform to the operation in FIG. 9 and FIG. 10. Therefore, while the seat 3 elevates the center of gravity G to conform to the operation of the knee (NE) and the vicinity of hip (HP) with the ankle (AN) of the seated person being the pivoting fulcrum and the seat 3 operates so that the operation tip is lower than the operation base end, and thus, a problem such as making the seated person uncomfortable in his/her knees (NE) or vicinity of hip (HP), or applying an undesirable load does not occur.

(44) Thus, the chair according to the present embodiment comprises the support mechanism 2, wherein the support mechanism 2 includes the guide surfaces 23a, 23b, 25a, and 25b formed along a predetermined trajectory for moving the seat 3 in the front-rear direction and in the left-right direction; the followers 24a, 24b, 26a, and 26b configured to perform a slide operation following the guide surfaces 23a, 23b, 25a, and 25b, and is configured to operatively supports the seat 3 by a relative operation of the guide surfaces and the followers. The support mechanism 2 comprises; the seat inclining mechanism Q being the seat inclining function configured to downwardly incline a tip side in an operation direction of the seat 3 when the 3 operates from a predetermined reference position(S), and further comprises: a return-force generation mechanism configured to generate, in accordance with an amount of movement, a return force in a direction of returning, to the reference position(S), the seat 3 having operated in a movement direction from the reference position.

(45) With such a configuration, the chair according to the present embodiment by accordingly setting the trajectory of the guide surfaces 23a, 23b, 25a, and 25b and the center-of-gravity movement mechanism P as the return force generation mechanism, not only suitably maintains the posture of the seated person during sitting, but can also suitably support the movement of the seated person during sitting. That is, even if the seated person moves the center of gravity to the front, rear, right, and left, it is possible to provide a most appropriate trajectory by bringing the follower 24a, 24b, 26a, and 26b along the guide surface 23a, 23b, 25a, 25b, it is designed such that no large falling moment is exerted on the support mechanism 2, and thus, it is possible to reduce a need for the seated person to brace his/her feet to the floor to rest in a proper posture. In addition, it is possible to provide a trajectory appropriate for each of the front-rear direction and the left-right direction, and thus, even if the body movement of the seated person is different between the front and the rear, or even if the body movement of the seated person is different between the front-rear and the left-right, it is still possible to realize a support state properly corresponding to the body movement of the seated person. Additionally, in the present embodiment, the guide surface and the follower are appropriately configured so as to be more comfortable for the seated person, and thus, a support state properly corresponding to the body movement of the seated person is realized.

(46) Further, it is not highly necessary for the seated person to brace his/her feet to the floor to assure balance, and thus, even if the lower end of the leg 1 is supported by the casters 12, a risk of the caster 12 running in an unexpected direction can be reduced, allowing for a stable use of the chair. In particular, the seat 3 supported by the above-described support mechanism 2 can be set not to perform a monotonous pivotal operation around a certain fulcrum close to the floor, and thus, the pivotal trajectory of the seat 3 can be accorded with or close to the operation below the knee of the seated person, as a result of which a proper support state is realized in which the feet do not get stuck even when inclining forward.

(47) Further, with the support mechanism 2, there is no problem that the seat and the leg sink down every time the seated person sits down, and there is no inconvenience caused as in the case where the lower end of the supporting post comes in contact with the floor for pivoting. Thus, when the seat surface 3a inclines, the seat of the chair of the present invention moves in the direction of the inclination, and thus, the chair extraordinarily well can fit to the body movement of the seated person.

(48) That is, according to the present invention, a chair is realized in which the seated person can perceive a comfortable sitting feeling even if sitting for a long time, and furthermore a high work efficiency can stably be maintained.

(49) Additionally, in the present embodiment, the leg 1 includes a lifting and lowering mechanism having the gas spring 14, the seat 3 is arranged above the lifting and lowering mechanism, and the support mechanism 2 is interposed between the lifting and lowering mechanism and the seat 3, and thus, a compact configuration is realized, instead of a complicated structure in which the support mechanism 2 is merged with the lifting and lowering mechanism.

(50) Additionally, in the present embodiment, when the return-force generation mechanism is constructed as the center-of-gravity movement mechanism P configured to elevate the center of gravity G of the seat 3 in accordance with the operation of the seat 3 from the reference position (S), the return-force generation mechanism is realized with a simpler configuration. In particular, in the present embodiment, with a combination of the operations by the center-of-gravity movement mechanism P and the above-described seat inclining mechanism Q, even in an operation in which the seat surface 3a is inclined forward, the seated person does not easily take a posture in which the feet of the seated person get stuck, and thus, it is possible to further improve a comfort during sitting.

(51) Further, in the present embodiment, the leg 1 includes a rotation support mechanism 16 configured to support the seat 3 horizontally rotatably, and thus, the movement of the seated person during work may be more suitably followed.

(52) Further, in the present embodiment, the support mechanism 2 is configured to support the seat 3 independently and operatively in each of at least the front-rear direction and left-right direction along a predetermined trajectory, and thus, each of the forward, backward, rightward, and leftward operations of the seat 3 can be smoothly performed.

(53) Additionally, in the present embodiment, the operation angle and the operation distance of the seat 3 in the front-rear direction are set so as to be larger than those in the left-right direction, so that the operation of the seat 3 is properly adapted to the movement of the seated person, and the operation angle of the seat 3 in a rear direction is set to be larger than that in a front direction, so that the operation of the seat 3 is adapted more properly to the movement of the seated person.

(54) Further, in the present embodiment, the support mechanism 2 includes the front-rear support unit 22 configured to operatively support the seat in the front-rear direction and the left-right support unit 21 configured to operatively support the seat in the left-right direction, where the left-right support unit 21 is configured separately from the front-rear support unit 22. The return-force generation mechanism includes a front-rear return unit configured to generate a return force in the front-rear direction and a left-right return unit configured to generate a return force in the left-right direction, where the left-right return unit is configured separately from the front-rear return unit. Thus, it is possible to maintain a comfortable sitting posture while individual components are simply configured. In particular, in the present embodiment, the front-rear support unit 22 and the left-right support unit 21 are arranged to be layered at an overlapping position in planar view, and thus, a whole chair is compact in planar view.

(55) Further, the front-rear support portion 22 is arranged above the left-right support portion 21, and thus, the movement of the seated person performing a greater and more frequent operation in a front-rear direction more than a left-right direction, may be more suitably followed.

(56) Additionally, in the present embodiment, by configuring the guide surfaces 23a, 23b, 25a, and 25b so as to form an upward curved shape, a precise and smooth operation of follower 24a,24b,26a, and 26b is realized, contributing to providing a more comfortable sitting feeling.

(57) Particularly, in the present embodiment, the leg 1 includes the casters 12, and thus, it is possible to prevent the chair from easily moving even if the seat 3 operates forward, rearward, rightward, or leftward while the seated person can move together with the chair while being seated when required. This eliminates an element for gripping the floor surface by frictional force to operate the seat 3 during sitting, unlike in Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 10-513374.

(58) Particularly, in the present embodiment, in order to realize the above-described behavior of the chair 3 with the support mechanism 2 alone, the support mechanism 2 is configured to move the supporting locations to the seat 3 to the front, rear, right, and left by combining the front support structure including the front guide surface 25a and the front follower 26a and the rear support structure including the rear guide surface 25b and the rear follower 26b, configured to directly or indirectly support the bottom surface of the seat 3 at two locations in the front-rear direction, and the left support structure including the left guide surface 23a and the left follower 24a and the right support structure including the right guide surface 23b and the right follower 24b, configured to directly or indirectly support the bottom surface of the seat 3 at two locations in the left-right direction, the supporting locations being configured to draw a trajectory along which the tip side in a movement direction of the seat 3 is downwardly inclined in accordance with the movement, and the support mechanism 2 further includes a return-force generation mechanism configured to generate, in accordance with the amount of movement, the return force in the direction of returning the supporting locations to the seat 3 having moved from the reference position (S) in the front-rear or left-right direction, to the reference position (S).

(59) As a specific mode of an implementation, in the present embodiment, a configuration so that, as the front-rear supporting locations supported by the front-rear support unit 22 are moved in the front direction from the reference position (S), the front-side supporting location is relatively lower than the rear-side supporting location, and as the front-rear supporting locations are moved in the rear direction from the reference position (S), the rear-side supporting location of the seat 3 is relatively lower than the front-side supporting location, is applied. Alternatively, a configuration so that as the left-right supporting locations supported by the left-right support unit 21 are moved in the left direction from the reference position (S), the left-side supporting location is relatively lower than the right-side supporting location, and as the left-right supporting locations are moved in the right direction from the reference position (S), the right-side supporting location of the seat 3 is relatively lower than the left-side supporting location, is applied. Here, the “supporting locations” are naturally contact points or contact portions between the front, rear, right, and left guide holes 23a, 23b, 25a, and 25b and the front, rear, right, and left followers 24a, 24b, 26a, and 26b. Further, in a process of the operation of the seat 3, the contact points or contact portions may change vertically. Particularly, if the center of gravity of the seated person is not between the supporting locations, the contact points or the contact portions may change vertically.

(60) It is noted that, even if the seated person moves the center of gravity to the front, rear, right, and left, as long as the seat 3 has its center of gravity located between the supporting locations arranged at two locations in the front-rear direction, or as long as the seat 3 has its center of gravity located or supporting locations arranged at two locations in the left-right direction, it is easy to design such that no large falling moment is exerted on the support mechanism 2, and thus, it is possible to reduce a need for the seated person to brace his/her feet to the floor to rest in a proper posture. And thus, as it is possible to provide, without a backlash, a trajectory appropriate for each of the front-rear direction and the left-right direction, and thus, even if, such as in an office chair, the body movement of the seated person differs between the front and the rear, or even if the body movement of the seated person differs between the front-rear and the left-right, a support state properly corresponding to the body movement of the seated person is realized.

(61) Particularly, in the present embodiment, in order to realize the above-described behavior of the chair 3 with the support mechanism 2 alone, the support mechanism 2 interposed between the leg 1 and the seat 3 includes the guide surfaces 23a, 23b, 25a, and 25b formed along a predetermined trajectory for moving the seat 3 in the front-rear direction and the left-right direction, and followers 24a, 24b, 26a, and 26b configured to perform a slide operation following the guide surfaces 23a, 23b, 25a, and 25b, and is configured to operatively support the seat 3 by a relative operation of the guide surfaces 23a, 23b, 25a, and 25b and the followers 24a, 24b, 26a, and 26b, the support mechanism 2 is so configured to draw a trajectory along which the tip side in a movement direction of the seat 3 is downwardly inclined when the seat 3 operates from a predetermined reference position(S), and further comprises: a return-force generation mechanism configured to generate, in accordance with an amount of movement, a return force in a direction of returning, to the reference position, the seat having moved in a front-rear or left-right direction from the reference position.

(62) Further, in the present embodiment, the support mechanism 2 has the slowing portion including a low repulsion surfaces 23a1, 23b1, 25a1, 25b1 and a high repulsion surfaces 23a2, 23b2, 25a2, and 25b2 configured to slow the operation of the followers 24a, 24b, 26a, and 26b toward the operation end of the followers 24a, 24b, 26a, and 26b, and thus, it is possible to effectively avoid a situation in which the seated person is given an undesirable “fear” or discomfort due to an unintended abrupt operation of the seat 3.

(63) In addition, in the present embodiment, the support mechanism includes the shockless unit R configured to avoid or absorb a shock caused by a collision between the end of the guide surfaces 23a, 23b, 25a, and 25b and the followers 24a, 24b, 26a, and 26b at the operation end, and thus, an undesirable shock and noise due to the abrupt operation of the seat 3 is not inflicted on the seated person.

(64) A modification of the present invention, as well as other embodiments, will be described below. In the following modifications and embodiments, elements corresponding to constituent elements of the embodiment described above will be referred to by the same reference numerals and detailed description thereof will be omitted.

(65) [Modification]

(66) In FIG. 11, a support housing 20F is illustrated instead of the support housing 20 disclosed in the above-described embodiment. That is, in the above-described embodiment, in order that the left-right support unit 21 and the front-rear support unit 22 are positioned by the support housing 20 at an overlapping position in planar view, each portion configuring the front-rear support unit 22 and the left-right support unit 21 is configured to be layered in an up-down direction; however, the support housing 20F is configured so that the front-rear support unit 22 and the left-right support unit 21 overlap in the up-down direction. Needless to say, in the modification, a configuration of a portion in the vicinity of the upper end of the leg 1 of the chair and a portion in the vicinity of the seat receiver 31 may be accordingly changed in accordance with a shape of the support housing 20F.

(67) With the configuration, when a pair of left-right support units 21 in the front-rear direction and a pair of front-rear support units 22 in the right-left direction are configured at the same height position, a chair compact in the up-down direction can be provided while realizing an operation similar to that in the above-described first embodiment.

(68) Further, FIG. 12 illustrates a schematic plane cross-section of a support housing 20N used instead of the support housing 20 disclosed in the above-described embodiment. That is, in the above-described embodiment, in order that the left-right support unit 21 and the front-rear support unit 22 are positioned by the support housing 20 at an overlapping position in planar view, each portion configuring the front-rear support unit 22 and the left-right support unit 21 is configured to be layered in the up-down direction; however, the support housing 20N is configured so that the front-rear support unit 22 and the left-right support unit 21 are nested (the front-rear support unit 22 being inside and the left-right support unit 21 being outside respectively) to overlap in both planar view and front view (not illustrated). Needless to say, in the modification, a configuration of a portion in the vicinity of the upper end of the leg 1 of the chair and a portion in the vicinity of the seat receiver 31 may be accordingly changed in accordance with a shape of the support housing 20N.

(69) In this configuration, similarly to above, when a pair of left-right support units 21 in the front-rear direction and a pair of front-rear support units 22 in the right-left direction are configured at the same height position, a chair compact in the up-down direction can be provided while realizing an operation similar to that in the above-described first embodiment.

(70) Further, another modification of the above-described shockless unit R is illustrated in FIG. 13A and FIG. 13B. That is, FIG. 13A and FIG. 13B illustrate a mode in which when an elastic means R1 such as a tensile coil spring arranged in a fixed portion of the chair is connected to the front and rear followers 26a, 26b so that the seat 3 biases toward the reference position (S), the shockless unit R as described above is configured. Further, in FIG. 13A and FIG. 13B, the biasing directions of the elastic means R1 differ; however, these are similar in that in the both cases, the front and rear followers 26a, 26b are biased so that the seat 3 reaches the reference position (S).

Second Embodiment

(71) A chair according to a second embodiment of the present invention may be suitably utilized as a rotating chair. The chair is similar to that in the above-described embodiments in that the leg 1 coming in contact with the floor surface and the seat 3 provided above the leg 1 are provided. Further, in the present embodiment, for convenience of illustration, in the seat 3, only the seat receiver 31 of sheet form is illustrated; however, the seat 3 similar in mode to the above-described embodiments may be applied. Unlike the seat 3 according to the above-described embodiments, a mode in which the backrest 4 is not integrally provided may be applied to the seat 3, and a conventional configuration may be widely applied to the seat 3.

(72) Further, the leg 1 is similar in configuration to the above-described embodiments other than the configuration in which the rotation support mechanism 16 as a part of the leg 1 configured to rotatably support the seat 3 is not provided, and thus, the description will be omitted. Further, the chair according to the present embodiment is similar to that in the above-described embodiments in that the support mechanism is configured across the upper end portion of the leg 1 to the seat receiver 31.

(73) However, because the chair according to the present embodiment differs in configuration of the support mechanism from that in the above-described embodiments, in addition, the return force generating mechanism as the seat inclining machine and the seat inclining mechanism Q are also configured in a different mode.

(74) That is, the chair according to the present embodiment is similar to that in the above-described embodiments in that it has the support mechanism interposed between the leg 1 and the seat 3, the support mechanism being configured to operatively support the seat 3 by the relative operation between the guide surface and the follower, and the support mechanism including the guide surface formed along a predetermined trajectory along which the seat 3 is operated in the front-rear direction and the left-right direction and the follower configured to perform the sliding operation following the guide surface. A difference is that when the chair is so configured that the guide surface is an integrally formed guide curved surface 83 and a plurality of followers or sliding contact followers 82 can operate in any direction of the front and rear directions and right and left directions along the guide curved surface 83, a guide support mechanism 8 is provided which can serve a role as a rotation support mechanism configured to rotatably support the seat 3 in the horizontal direction, in addition to a role of the support mechanism providing the same effect as in the above-described embodiments.

(75) As illustrated in FIG. 14 to FIG. 17, in order to operatively support the seat 3 along a predetermined trajectory, along which the seat is operated in the front-rear direction and left-right direction, the guide support mechanism 8 interposed between the leg 1 and the seat applies a configuration having a guide board 81 having a guide curved surface 83 of substantially conical shape or truncated cone shape and a sliding contact follower 82 that can slide on the guide curved surface 83 in any direction. This guide support mechanism 8 is configured to be interposed between the upper end portion of the leg 1 and the lower end portion of the seat receiver 31.

(76) The guide board 81 is formed of a hard material fixed at the upper end of the leg 1. The guide board 81 is so shaped that a portion in the vicinity of an outer edge is dented downwardly into a substantially exact circular shape in planer view, and further a portion surrounded by the dented portion is elevated into a substantially truncated cone shape so as to be gradually higher toward a center portion. In addition, the elevated portion formed by denting the portion in the vicinity of the outer edge is configured as a restriction wall 84 configured to restrict an operation range of the sliding contact follower 82, and the curved surface surrounded by the restriction wall 84 is configured as the guide curved surface 83. Specifically, the shape of the guide curved surface 83 has a curved surface shape such that the degree of inclination gradually becomes larger as being closer to the center of the guide board 81 from the vicinity of an outer periphery thereof. Note that in the present embodiment, the center of the guide board 81 is configured in a planar form; however, the sliding contact follower 82 is set to not slide over the planar portion. Further, the guide curved surface 83 and the restriction wall 84 have a continuous part continuous on a curved surface, and at this continuous part, a slowing portion configured to slows the movement of the sliding contact 82 in accordance with its closeness to an operation end of the follower are formed. In addition, a shockless portion R which avoids or absorbs the impact caused by the collision of the sliding contact follower 82 with the regulating wall 84 is formed.

(77) In the present embodiment, the sliding contact follower 82 is arranged with respect to the seat receiver 31 at six locations being at least three or more locations allowing for a stable self-standing, so that each location corresponds to a relative position corresponding to each vertex of an equilateral hexagon in planar view. In another words, the sliding contact follower 82 is arranged at a relative position which can be arranged in equal intervals on the outline of the exact circle. The sliding contact follower 82 includes a follower main body 85 having a substantially spherical shape slidingly contacting the guide curved surface 83 and a seat supporting post 86 of which the lower end portion is supported by the follower main body 85 and of which the upper end portion is fixed to the seat receiver 31.

(78) An operation of the seat 3 according to the present embodiment will be described, below. FIG. 14 illustrates only the seat receiver 31, however, it is a behavior or the seat receiver 31 at a predetermined reference position (S) at which the seat 3 rests by its own weight, and FIG. 17 illustrates a behavior of the seat receiver 31 when the seat 3 operates in any direction. In the present embodiment, not only in a state illustrated in FIG. 17, but also when the seat 3 operates from the reference position (S) into any direction, its operation is against the gravity. Specifically, the guide curved surface 83 being a guide surface is provided so that there are always, of the six sliding contact followers 82, some sliding contact followers 82 ascending and the other sliding contact followers 82 descending, during the operation of the seat. As a result, in the configuration of the present embodiment, the position of the center of gravity of the seat receiver 31 rises from the reference position (S). Further, at this time, a return force exerted by the gravity in a direction of returning the seat 3 to the reference position (S) is spontaneously applied to the seat 3. That is, in the present embodiment, the guide curved surface 83 and the sliding contact follower 82 are the return-force generation mechanism and function as the center-of-gravity movement mechanism P configured to elevate the center of gravity G of the seat 3 in accordance with the operation of the seat 3 from the reference position (S). In addition, the seat receiver 31 that has operated is in a posture in which the operation tip side is descended. As described above, this results from the feature that the guide curved surface 83 is in a substantially truncated cone shape. That is, in the present embodiment, the guide curved surface 83 also functions as the seat inclining mechanism Q.

(79) <Modification>

(80) In the above-described present embodiment, a mode is disclosed in which each of the six sliding contact followers 82 is firmly fixed to the seat receiver 31; however, as illustrated in FIG. 18, needless to say, a spring 87 may be separately arranged in the sliding contact follower 82.

(81) In the present modification, in addition to the follower main body 85 and the seat supporting post 86 similar to those in the above-described embodiment, the sliding contact follower 82 further includes a spring 87 interposed between the seat supporting post 86 and the seat receiver 31. In the spring 87, a pressure coil spring of which the upper end portion is fixed to the seat receiver 31 side and the lower end portion is fixed to the upper end portion of the seat supporting post 86, is installed. This results in reducing a shock applied to the seated person during sitting being relieved, and contributes to smoother operation of the seat 3.

(82) Further, as illustrated in FIG. 18, needless to say, the number of the sliding contact followers 82 is not limited to six, of course if it is three or more that can be configured to be self-standing, and seven or more sliding contact followers 82 may be arranged concentrically. It is noted that in the modification, 18 sliding contact followers 82 are arranged concentrically.

(83) According to the configuration as described above, when the chair according to the present embodiment and the modification is configured to conform to accomplish an operation and effect similar to those in the first embodiment.

(84) In particular, in the present embodiment, when it is so configured that the guide surface is the integrally formed guide curved surface 83, and a plurality of followers or the sliding contact followers 82 can freely contact slidingly along the guide curved surface 83 in any direction of the front and rear directions and the left and right directions, in any direction, it is possible to integrally configure the support mechanism similar to that in the above-described embodiments and the rotation support mechanism similar to the rotation support mechanism 16 that is one constituent element of the leg 1 in the above-described embodiments to realize a compact chair as a whole.

(85) In addition, in the present embodiment, when there are a plurality of sliding contact followers 82, specifically, three or more sliding contact followers 82, and the guide curved surface 83 is set so that there are always, of the plurality of sliding contact followers 82, some sliding contact followers 82 ascending and the other sliding contact followers 82 descending, during the operation of the seat 3, it is possible to more simply configure the center-of-gravity movement mechanism P similar to that in the above-described embodiments.

(86) In addition, in the present embodiment, a smooth operation of the seat 3 can be realized by configuring so that the guide curved surface 83 being a guide surface has a substantially conical shape.

(87) In particular, in the present embodiment, when it is so configured that the sliding contact follower 82 always contacts the guide curved surface 83 at three or more locations, the sliding contact follower 82 stably contacts the guide curved surface 83, as a result of which it is possible to stably support the seat receiver 31 and the seat 3 as well.

(88) Thus, an embodiment of the present invention has been described, and a specific configuration of each unit is not limited to that in the embodiments described above and various modifications are possible without departing from the gist of the present invention.

(89) For example, the relationship between the follower and the guide surface may be exchanged.

(90) Further, it may be configured so that the seat can be operated by relative movement of the guide surface and the follower at least in front-rear direction, so that it is impossible to operate in the left and right directions, or it can be operated by another means. Examples of a left-right support unit for making left and right operates include a left-right support unit using a link mechanism swinging along a predetermined trajectory, and a right and left rotation support unit rotating and swinging in a left-right direction around a shaft extending in the front-rear direction.

(91) Further, in the above-described embodiments, only a mode in which the backrest is provided integrally with the seat is disclosed; however, naturally, a mode in which the backrest is provided separately from the seat, and a mode in which while the seat and the backrest are provided separately, a synchro-tilt mechanism in which the backrest may operate in response to the operation of the seat is provided may also be acceptable. In particular, when the backrest is provided in the front-rear support unit and/or the seat, it is possible to obtain the synchro-tilt mechanism with a simple configuration.

(92) Further, in order to eliminate the lifting of the heel of the seated person during the backward tilting operation, a bending function of bending the front portion of the seat may be provided. In this case, in association with the front-rear support unit, the seat may be supported at three locations in the front-rear direction.

(93) Further, although an elbow is not disclosed in each of the embodiments described above, of course, provision of the elbow shall not be precluded in each of the embodiments described above. In particular, in a case of a chair directly or indirectly provided with the elbow in the vicinity of the upper end of the leg, the elbow does not operate forward, rearward, rightward, and leftward in conjunction with the operation of the seat, and thus, a further sense of safety can be given to the seated person.

(94) In addition, all of the embodiments described above disclose the center-of-gravity movement mechanism P as the configuration of the return-force generation mechanism, and naturally, provision of an elastic means such as a spring shall not be precluded as long as it is configured to return the seat to the reference position.

(95) Further, a “buffer means” configured to buffer a bumping feeling upon reaching the operation end of the seat may be provided between the seat or the backrest, and the support mechanism, or within the support mechanism. Specific examples include a buffer member provided either in a contact unit provided on the bottom surface side of the seat or on a unit to be contacted provided on an outer wall of the support mechanism, and an elastic member being provided at the end of the guide holes in the support mechanism and coming in contact with a follower.

(96) Further, in each of the above-described embodiments, the seat is held at the reference position by exclusively using its own weight of the seat; however, a “reference position holding means” may be provided so that any reference position can be set. A specific example may include a balancer, provided in the seat, adjustable a position of the center of gravity of the seat. Further, a lock means configured to lock the seat at the reference position when the seated person does not sit and to unlock the seat when the seated person sits may be provided as a part of the support mechanism. With such a means, the seated person may easily sit on the seat at the reference position while suppressing undesirable swinging of the seat before sitting, and the seated person may obtain a desirable sitting comfort as a result of being unlocked by sitting.

(97) In addition, it is possible to apply various modifications to another detailed configuration such as a specific shape or material of the seat without departing from the gist of the present invention.

INDUSTRIAL APPLICABILITY

(98) The present invention can be applied to a chair suitably applicable to an office rotating chair and the like.

DESCRIPTION OF REFERENCE NUMERALS

(99) 1 Leg 16 Rotation support mechanism 2 Support mechanism 21 Left-right support unit 22 Front-rear support unit 3 Seat 4 Backrest 8 Support mechanism (guide support mechanism) 81 Guide board 82 Follower (sliding contact follower) 83 Guide surfaces (guide curved surface) G Center of gravity P Return-force generation mechanism (center-of-gravity movement mechanism) Q Seat inclining function (seat inclining mechanism) S Reference position