A tiltable chair includes a flexible seat body including an integrally formed seat back and seat surface is supported on a seat frame disposed on upper parts of legs, and the seat back connected to a back frame allowing tilting rearwards, the position of the connection being in an area around the upper part of the pelvis of a person seated thereon. A guide rail having an arc-shaped groove is fixed to the seat frame, and guide members which engage and roll in the arc-shaped grooves are pivotably supported on a shaft bracket of the rear surface of the seat surface. The arc-shaped groove has a high center so that the seat surface undergoes curved motion forward and upward such that the ischium is positioned lower than the lower part of the knees when the seat back tilts rearwards.

A motion seat is described that includes a chassis, a seat frame, a seat cushion, a backrest, and a resilient hinge. The seat frame is attached to the chassis and the seat cushion and the backrest are each attached to the seat frame. The resilient hinge formed as a unitary body and may be formed from a resilient polymer. The seat cushion and/or the backrest is pivotably attached to the seat frame with the resilient hinge

A motion seat is described that includes a chassis, a seat frame, a seat cushion, a backrest, and a resilient hinge. The seat frame is attached to the chassis and the seat cushion and the backrest are each attached to the seat frame. The resilient hinge formed as a unitary body and may be formed from a resilient polymer. The seat cushion and/or the backrest is pivotably attached to the seat frame with the resilient hinge

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.

A body support structure includes a frame and a membrane attached to the frame. The membrane includes elastomeric filaments. The membrane includes different regions with different stiffness. The membrane may form a part of a seat or a backrest.

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 adjustment device for a chair, comprising an oscillating mechanism composed of a first plate, associated with a central gas-operated post for the height adjustment of a seat. A second plate is articulated to the first plate so that it can oscillate, by means of a pair of first pivots and is fixed to a backrest. A linkage is articulated to the first plate, by means of a second pivot, and is in turn articulated, by a third pivot, to a third plate, with which the seat can be associated. The third plate is articulated to the second plate. Elements are associated with the linkage for connection to at least one slat or leaf spring, which is arranged on a plane that is substantially parallel to the plane of the seat and is adapted to elastically contrast the inclination of the second plate with respect to the first 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 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.