A mechanism for an office chair is structurally particularly simple and consequently comparatively inexpensive, but nevertheless extremely variable. Both the seat support and the backrest support are articulated by way of a common pivot axis. The seat support is connected in an articulated manner to the base support by way of at least one pivot bolt and is pivotable relative to the base support. The backrest support is connected in an articulated manner to the base support by way of the at least one pivot bolt and is pivotable relative to the base support.

Disclosed herein is a chair that includes a backrest portion, a seat portion coupled with the backrest portion, a column portion coupled with the seat portion, a linkage coupled with the backrest portion, a leaf spring in direct contact with the linkage, an arc-shaped toothed structure fixed translationally relative to the column portion, and a different toothed structure in contact with the arc-shaped toothed structure. The chair is also configured such that when a weight is applied to the seat portion, a fulcrum point of the leaf spring moves as the different toothed structure moves along the arc-shaped toothed structure to thereby shorten a working length of the leaf spring and provide an increased resistance to tilting of the backrest portion relative to the column portion. A process for assembling the chair and a weight-based tilt-resistance assembly for use with the chair are also described herein.

Disclosed herein is a chair that includes a backrest portion, a seat portion coupled with the backrest portion, a column portion coupled with the seat portion, a linkage coupled with the backrest portion, a leaf spring in direct contact with the linkage, an arc-shaped toothed structure fixed translationally relative to the column portion, and a different toothed structure in contact with the arc-shaped toothed structure. The chair is also configured such that when a weight is applied to the seat portion, a fulcrum point of the leaf spring moves as the different toothed structure moves along the arc-shaped toothed structure to thereby shorten a working length of the leaf spring and provide an increased resistance to tilting of the backrest portion relative to the column portion. A process for assembling the chair and a weight-based tilt-resistance assembly for use with the chair are also described herein.

A support mechanism for mounting a seat part to a foot part of a functional chair having a slide bearing which cooperates with a front section of the seat part, and a pivotable support part which is supported by a cantilever part and which is connected to a region of the seat part that is adjacent to the rear region of a seat surface section of the seat part.

A chair assembly includes a base assembly, a seat assembly having a pair of side edges and a fore-to-aft extending longitudinal centerline, a back assembly movable between upright and reclined positions, and an arm assembly including an arm base extending from a first location between the side edges to a second location laterally outward of one of the side edges, wherein the arm base extends at an acute angle with respect to the longitudinal centerline and at an upward angle from the first location toward the second location, a support assembly supported by and extending upwardly from the arm base, and an armrest supported by the support assembly that is adjustable to support the armrest between a plurality of selected vertical positions, wherein the arm assembly and back assembly move at a different rate from one another as the back assembly is moved between the upright and reclined positions.

A chair assembly includes a base assembly, a seat assembly having a pair of side edges and a fore-to-aft extending longitudinal centerline, a back assembly movable between upright and reclined positions, and an arm assembly including an arm base extending from a first location between the side edges to a second location laterally outward of one of the side edges, wherein the arm base extends at an acute angle with respect to the longitudinal centerline and at an upward angle from the first location toward the second location, a support assembly supported by and extending upwardly from the arm base, and an armrest supported by the support assembly that is adjustable to support the armrest between a plurality of selected vertical positions, wherein the arm assembly and back assembly move at a different rate from one another as the back assembly is moved between the upright and reclined positions.

A structure for chair backrest is disclosed. The chair includes a first support frame, a second support frame coupled to the first support frame, a seat section arranged between the first support frame and the second support frame. The first support frame includes a backrest mounted thereon. The first support frame includes a lower frame section and an upper frame section. The lower frame section and the upper frame section include, mounted therebetween, a supine inclination assembly that upon receiving a force acting thereon takes a movement for achieving an predetermined angle of supine inclination. In this way, easy adjustment of the angular position of the backrest may be achieved for comfortableness of the user, and excessive inclination that causes potential risk can be avoided so as to improve the utilization of the backrest of the chair.

An exemplary seat having seat connection mechanism for attaching the seat to a wheelchair includes a seat frame and a backrest. The backrest is pivotably connected to the seat frame through a pivoting mechanism. The seat further includes a biasing member connected to the backrest at a first connection point and a second connection point near the seat frame. The second connection point and the pivoting mechanism are spaced apart from one another by a distance C. The seat further includes an adjustment mechanism adapted for changing the distance C. The second connection point may be connected to a guide arm, such that the position of the second connection point is adjustable by sliding the second connection point along the guide arm, thus making the distance C adjustable.

A chair back assembly includes a back shell member including laterally extending top, bottom and side portions cooperating to define an open space therebetween, where a portion of the back shell member is located in a lumbar region, a cover having a first surface and a second surface opposite the first surface, wherein the cover covers at least a portion of the open space, and a back frame assembly operably supporting the back shell member and movable between upright and reclined positions, wherein the back frame assembly causes the back shell to flex in a fore-to-aft direction as the back frame assembly is moved between the upright and reclined positions independent of an external force being exerted on the back shell member, and where the lumbar portion of the back shell member remains spaced from the back frame as the back frame is moved between the upright and reclined positions.

A chair back assembly includes a back shell member including laterally extending top, bottom and side portions cooperating to define an open space therebetween, where a portion of the back shell member is located in a lumbar region, a cover having a first surface and a second surface opposite the first surface, wherein the cover covers at least a portion of the open space, and a back frame assembly operably supporting the back shell member and movable between upright and reclined positions, wherein the back frame assembly causes the back shell to flex in a fore-to-aft direction as the back frame assembly is moved between the upright and reclined positions independent of an external force being exerted on the back shell member, and where the lumbar portion of the back shell member remains spaced from the back frame as the back frame is moved between the upright and reclined positions.