To realize a noble, useful seat with a simple structure designed to follow a natural movement of a seated person in front-rear and left-right directions and to support appropriately a movement of the person continuously changing its posture while the person balances a load. The seat includes the elastic support layer 3 and upper and lower base units 4 and 5 arranged to sandwich the elastic support layer 3. The upper base unit 4 includes the rolling surface 42e bulging toward the lower base unit 5 thereabove via the elastic support layer 3, is rollable in a 360° direction from the tilt reference position IRP in receiving a load of the seated person, and has a moving distal end side tilting more downward as a distance from the position IRP increases, and is configured to move while compressing the elastic support layer 3 by the rolling surface.

A reclining seatback support device which mainly includes at least one seatback support and a seatback body is revealed. The seatback body and an upper end of the seatback support are provided with pivot bracket portions pivotally connected to each other while a lower part of the seatback body and the seatback support are connected by a swing arm. When a user is sitting and lying down on the back, the seatback body is rotated around the pivot axis where the seatback body is pivotally connected to the upper end of the seatback support and then reclined at a certain angle. By elastic segments of the seatback body and the swing arm between the lower part of the seatback body and the seatback support for pulling and limiting the seatback body, the user can lean on the seatback body comfortably and safely.

Joint arrangement (10) has a hollow cylindrical receiving cylinder (20) that extends in a cylinder axis direction (Z) and receives one end of a chair column (30) of an active-dynamic wobble chair, the latter movably mounted in a substantially hollow cylindrical outer joint shell (40) composed of joint shell segments (45). Movable mounting of receiving cylinder (20) is achieved by deformable elastic elements (50) arranged to be variable in shape and position in a bearing gap (60) between an outer wall portion (21, 22) of the receiving cylinder (20) and an inner wall portion (41, 42) of the joint shell (40). Receiving cylinder (20) is actuated in a force-dependent manner, whereby shape and/or position of the elastic elements (50) change as viewed in a radial direction (Rs) from changing, preferably reducing, clearance of the bearing gap (60) when the receiving cylinder (20) is actuated in a cylinder axis direction (Z).

A seat tilting device includes: a bottom plate secured to a seat base; a top plate secured to a seat; a pivot connecting the top plate to the bottom plate; a compression spring surrounding the pivot; and a compression ring surrounding the compression spring, wherein there is space between a bottom surface of the top plate and a top surface of the compression ring such that the top plate may tilt on the pivot until it contacts the top surface of the compression ring and the movement of the top plate is resisted by the compression spring.

An adjustable chair can support an occupant that sits on a front portion of a seat cushion. When the user leans back, the chair can provide back support without requiring that the user slide rearwardly along the seat cushion, thereby providing back support to minimize, limit, or substantially eliminate lower back fatigue, discomfort, or the like. A back support of the chair can be located at a desired forward/rearward position based on the user's position on the seat. In some settings, the chair can be used by a card dealer who tends to sit on a forward portion of the seat when dealing cards. The back support can be positioned to comfortably support the dealer's back when, for example, the dealer sits generally upright. The chair can also be used by other individuals that frequently sit on the front of the seat cushion.

A seat tilting device includes: a bottom plate secured to a seat base; a top plate secured to a seat; a pivot connecting the top plate to the bottom plate; a compression spring surrounding the pivot; and a compression ring surrounding the compression spring, wherein a height of the compression ring is less than a distance between the bottom plate and the top plate, and wherein the compression spring biases the top plate away from the bottom plate.

A seat tilting device includes: a bottom plate secured to a seat base; a top plate secured to a seat; a pivot connecting the top plate to the bottom plate; a compression spring surrounding the pivot; and a compression ring surrounding the compression spring, wherein a height of the compression ring is less than a distance between the bottom plate and the top plate, and wherein the compression spring biases the top plate away from the bottom plate.

A seat tilting device includes: a bottom plate secured to a seat base; a top plate secured to a seat; a pivot connecting the top plate to the bottom plate; a compression spring surrounding the pivot; and a compression ring surrounding the compression spring, wherein there is space between a bottom surface of the top plate and a top surface of the compression ring such that the top plate may tilt on the pivot until it contacts the top surface of the compression ring and the movement of the top plate is resisted by the compression spring.

An adjustable chair can support an occupant that sits on a front portion of a seat cushion. When the user leans back, the chair can provide back support without requiring that the user slide rearwardly along the seat cushion, thereby providing back support to minimize, limit, or substantially eliminate lower back fatigue, discomfort, or the like. A back support of the chair can be located at a desired forward/rearward position based on the user's position on the seat. In some settings, the chair can be used by a card dealer who tends to sit on a forward portion of the seat when dealing cards. The back support can be positioned to comfortably support the dealer's back when, for example, the dealer sits generally upright. The chair can also be used by other individuals that frequently sit on the front of the seat cushion.

In view of various movement of a seated person, when giving the left-right swinging operation to the seat in the non-conventional aspect, a chair configured such that the back can perform a new movement suitable for the left-right movement of the seat and return to the predetermined position when the seated person leaves a seat, is realized. For the purpose, a back 6 is arranged behind a seat 5, and the back 6 has an operation mechanism 6M turning-movably supporting the load received from a seated person in a left-right direction in a front view, and when the load is applied, at least a part of guide part 65a, 66a of the operation mechanism 6M is separated and the back moves freely, and when the applied load is removed, the back automatically returns to the neutral position along the guide part 65a, 66a.