A chair includes: a leg 1; a seat 2; and a front-back support mechanism 4. The front-back support mechanism 4 is provided at a seat receiving part 50 directly supported by the leg 1, and the front-back support mechanism includes: a wavy plate 56 provided to horizontally extend from vertical walls 51 of the seat receiving part 50 and having mound-shaped surfaces 57, 58 each convexly curved upward; and followers 53, 54 provided at front-back support bodies 52 as supported parts and configured to move relative to the mound-shaped surfaces 57, 58 while contacting the mound-shaped surfaces 57, 58. The wavy plate 56 is associated with the followers 53, 54 such that a movement end inclines downward when the seat 2 moves from a neutral position in accordance with a relative movement between the mound-shaped surfaces 57, 58 and the followers 53, 54.

A chair includes: a leg 1; a seat 2; and a front-back support mechanism 4. The front-back support mechanism 4 is provided at a seat receiving part 50 directly supported by the leg 1, and the front-back support mechanism includes: a wavy plate 56 provided to horizontally extend from vertical walls 51 of the seat receiving part 50 and having mound-shaped surfaces 57, 58 each convexly curved upward; and followers 53, 54 provided at front-back support bodies 52 as supported parts and configured to move relative to the mound-shaped surfaces 57, 58 while contacting the mound-shaped surfaces 57, 58. The wavy plate 56 is associated with the followers 53, 54 such that a movement end inclines downward when the seat 2 moves from a neutral position in accordance with a relative movement between the mound-shaped surfaces 57, 58 and the followers 53, 54.

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).

A chair comprises: a leg 1 erected on a floor surface; a seat 3 arranged above the leg 1; and a support mechanism 8 interposed between the leg 1 and the seat 3, wherein the support mechanism 8 is arranged below the seat 3 and is configured to movably support the seat 3 along a predetermined trajectory by having an omnidirectional connection unit 72 configured to operably connect in all directions including the front-rear direction and the left-right direction, comprises: a seat inclining function configured to downwardly incline a tip side in a movement direction of the seat 3, and further comprises: a return-force generation mechanism configured to generate, by elevating a center of gravity of the seat 3, a return force in a direction of returning the seat 3 to the reference position.

A housing for a tilt mechanism for a chair, in particular for an office chair, has a receptacle for a chair column, a seat support integrated in the housing or a seat-support mounting apparatus for fastening a seat support to the housing, and a backrest-support mounting apparatus for fastening a backrest support to the housing.

A seating furniture includes a seat with a seat surface, a pedestal and a tilt mechanism. The tilt mechanism is disposed between the pedestal and the seat and permits an inclination of the seat surface of the seat relative to the horizontal. In addition, the tilt mechanism has a lower bearing block mounted to the pedestal, and an upper bearing block fixedly connected to the seat. The lower bearing block has a convexly curved lower bearing surface on its upper side facing the upper bearing block, and the upper bearing block has a concavely curved upper bearing surface on its lower side facing the lower bearing block. The lower and upper bearing surfaces have substantially corresponding radii of curvature, so that the upper bearing block can be moved relative to the lower bearing block along the upper bearing surface. A tilt mechanism for seating furniture is also provided.

A stool comprises a height-adjustable seat. The seat is coupled to a stem of the stool using a ball and socket mechanism. The ball and socket mechanism enables the seat to be tiltable up to 20 degrees in all directions about a vertical axis. The ball and socket mechanism aids in providing the seated individual with an increased range of motion. The range of tiltable motion can be adjusted using an adjustment member.

A stool comprises a height-adjustable seat. The seat is coupled to a stem of the stool using a ball and socket mechanism. The ball and socket mechanism enables the seat to be tiltable up to 20 degrees in all directions about a vertical axis. The ball and socket mechanism aids in providing the seated individual with an increased range of motion. The range of tiltable motion can be adjusted using an adjustment member.

A guide spring for a seating device has an inner portion, an outer portion, and a spiral coiled portion extending more than one convolution between the inner portion and the outer portion. The inner portion is firmly attached to a rod and the outer portion is firmly attached to a body. The guide spring thereby secures a radial position of the rod within the body, allowing the rod to move axially relative to the body when a load is placed onto the seating device. When in use, the guide spring deforms from a flat spiral shape to a conical spiral shape with axial movement of the rod relative to the body.

A guide spring for a seating device has an inner portion, an outer portion, and a spiral coiled portion extending more than one convolution between the inner portion and the outer portion. The inner portion is firmly attached to a rod and the outer portion is firmly attached to a body. The guide spring thereby secures a radial position of the rod within the body, allowing the rod to move axially relative to the body when a load is placed onto the seating device. When in use, the guide spring deforms from a flat spiral shape to a conical spiral shape with axial movement of the rod relative to the body.