The object of the invention is a convertible, dual function chair for sitting and kneeling, which gives the possibility of changing the position and relieving the spinal column during a prolonged work in a sitting position.

The dual function chair for sitting and kneeling is equipped with a movable backrest and headrest support, shaped in the lower part in such a way that its displacement changes the size of the chair simultaneously vertically and horizontally. It is also equipped with a sliding-rotating-returning or a sliding-returning backrest device, which makes it follow the user's back and support it accurately at every angle of inclination of the backrest when tilting the backrest. It is also equipped with a headrest connected to the headrest arm through a rotary-sliding mechanism, which rotationally connects with the backrest support, and has a specially shaped five-star base, in which the arms, apart from the fragment above the wheels, are maximally flattened and located as low as possible above the ground.

A chair can include a chair back, or backrest, that is coupled to a base of a chair above a seat of the chair. A tilt mechanism can attach the backrest to the base at spaced apart locations. In some embodiments, the tilt mechanism can be configured so that the backrest rotates about multiple pivots as it reclines from an upright position to a reclined position to drive forward motion of the seat during recline of the backrest.

The chair is of the type with mutually synchronous adjustment between back inclination and seat inclination, namely via a region between a respective zero position of back inclination (R.sub.0) and seat inclination (S.sub.0) and a respective maximum back inclination and seat inclination. The chair has a substructure (1) which is intended for placing on the floor and on which a base (2) is fastened rigidly. A seat support (6) which has a seat region and a back region is connected to the base (2). Furthermore, the chair includes two backrest bows (3) which are deflectable differently with respect to each other and are fastened on one side to the base (2) and on the other side to the back region of the seat support (6). The two backrest bows (3) are coupled independently of each other to the base (2) on a stationary first axis of rotation (D1). The seat region of the seat support (6) is coupled to the base (2) on a stationary second axis of rotation (D2). The two backrest bows (3) are coupled independently of each other to the back region of the seat support (6) on an elastically deformable third axis of rotation (D3). The back region of the seat support (6) is twistable elastically. The seat support is covered with a cover. In the configuration as an office swivel chair, a height-adjustable pneumatic spring (12) on which the base (2) rests in order to adjust the seat support (6) to a height corresponding to a user's needs and in order to configure said seat support (6) to be rotatable about a vertical axis (V) is arranged in the substructure (1).

Some embodiments relate to a chair including a base, a hub, and a seat frame. The hub is supported by the base and includes first and second side mounts and first and second covers. The first side mount is positioned on a first side of the chair and includes a back portion and a bottom portion. The first cover is coupled to the first side mount to define a first channel with the first side mount. The seat frame includes a first lateral member having a lower portion and an upper portion that is pivotally coupled to the back portion of the first side mount and is configured to angulate relative to the lower portion. The lower portion of the first lateral member is slidably received in the first channel such that two sides and a bottom of the lower portion received within the first channel are substantially hidden.

A tilt control system includes a spring adjuster and compression spring, which may be removed in an unstressed condition. The tilt control system may also include a variable back stop having curved transition surfaces between the stop surfaces. A lumbar compensator may be integrated into a backrest, which may be coupled with a quick release to the base and actuated by sliding engagement with the seat.

A pivoting mechanism with a first member, a second member pivotally engaged with the first member to pivot about a pivot axis, and pivoting resistance mechanism with a spring housing disposed in the first member spaced from the pivot axis, a spring disposed in the spring housing, and a deflecting member that projects from the second member spaced from the pivot axis to engage the spring disposed in the spring housing. The first member can be a chair mechanism body, and the second member can be a pivoting support, such as for a chair bottom or back. A height adjustment mechanism has a movable member, and a locking member, such as a screw, can be operative as a height locking mechanism with a first, restraining condition wherein actuation of the movable member is prevented and a second, non-restraining condition wherein actuation of the movable member is permitted.

An item of seating furniture (100), with backrest (101), seat surface (102), supporting structure and resetting mechanism (200), wherein the backrest (101) and the seat surface (102) are connected to the supporting structure. The backrest (101) is pivotable relative to the supporting structure about a pivot axis from a first position into a second position, and the backrest (101) is connected to the seat surface (102) via connector (103). The connector (103) is designed such that, when the backrest (101) pivots relative to the seat surface, the seat surface (102) is inclined relative to the supporting structure, wherein the resetting mechanism (200) are designed to exert a resetting force on the backrest (101) in the second position, the resetting force is directed in the direction of the first position, wherein the item of seating furniture (100) with setting mechanism (104) which is designed to set the resetting force.

A chair control assembly includes a base structure having first and second pivot points spaced from one another, a seat support structure coupled to the first pivot point, a back support structure coupled to the second pivot point and adapted to move between first and second positions, wherein the base structure does not move as the back support structure moves between the first and second positions, and a control link pivotably coupled to the seat support structure for rotation about a third pivot point and pivotably coupled to the back support structure for rotation about a fourth pivot point, wherein the third pivot point is rearward of the fourth pivot point when the back support structure is in the upright position, and the third pivot point moves forward relative to the fourth pivot point as the back support structure moves from the upright to reclined positions.

The invention is based on a mechanism (1) for a chair having a synchro mechanism by means of which a seat surface structure and a backrest structure are moved in a synchronized ratio relative to one another, wherein the mechanism (1) serves to adjust a restoring force of the synchro mechanism to a different body weight of a seat user by changing a working angle of a force accumulator, and the mechanism (1) includes a seat support (8) for the seat surface structure, a bearing yoke (5), the force accumulator unit (2) a backrest support (3) for supporting the backrest structure, and a translational bearing (16), wherein the mechanism (1) has a triangular steering block (21) and the force accumulator unit (2) is connected to the triangular steering block (21), and on a weight adjustment method for an improved dynamic sitting experience on the part of the seat user by means of a mechanism (1) for a chair with a synchro mechanism, in which the position of a first pivot point (31) of the force accumulator unit (2) is shifted by means of the adjuster (11) when the backrest support (3) is in a position (A), and a swivelling motion of the backrest support (3) into a second position (B) is not performed until the first step is completed.

The adjusting mechanism serves for the setting of a restoring force acting on the backrest of a chair. A back support and a seat support are fastened on a support. A setting mechanism configured in the manner of scissors is provided for the weight setting. Said setting mechanism has two scissor arms which are connected to one another via a scissor pin. One of said scissor arms is formed by a spring element and is fastened with its front-side spring end on said support. The back spring end is fastened on said scissor pin. Said first scissor arm is connected to said back support in the manner of a connecting rod. An active lever length is defined between said scissor pin and a support pin about which said back support is mounted pivotably. A compact construction mode is achieved by the configuration of said scissor arm as a spring element.