Abstract: A seating structure includes a central spine and an upper back structure having a pair of arms extending upwardly and outwardly from the central spine. The upper back structure is pivotally connected to the central spine about a first horizontal axis. A back support structure is pivotally connected to the spine about a second horizontal axis and is pivotally connected to the ends of each of the arms about a third horizontal axis.

Abstract: A seating structure includes a central spine and an upper back structure having a pair of arms extending upwardly and outwardly from the central spine. The upper back structure is pivotally connected to the central spine about a first horizontal axis. A back support structure is pivotally connected to the spine about a second horizontal axis and is pivotally connected to the ends of each of the arms about a third horizontal axis.

Abstract: A seating structure has an articulated seat and back. A rear portion of the seat is automatically pivotable relative to a forward portion of the seat as the seat is tilted between upright and reclined tilt positions. An upper portion of the back is pivotable relative to the lower portion between a neutral position and an extended position, with the upper portion being pivotable relative to the lower portion independent of the tilt position of the back. In one aspect, an adjustment mechanism is coupled between lower and upper back support members and pivots the upper support member between at least first and second support positions. A seat with an adjustable seat depth is also provided, along with various methods for operating the different aspects and embodiments of the seating structure.

Abstract: A seating structure has an articulated seat and back. A rear portion of the seat is automatically pivotable relative to a forward portion of the seat as the seat is tilted between upright and reclined tilt positions. An upper portion of the back is pivotable relative to the lower portion between a neutral position and an extended position, with the upper portion being pivotable relative to the lower portion independent of the tilt position of the back. In one aspect, an adjustment mechanism is coupled between lower and upper back support members and pivots the upper support member between at least first and second support positions. A seat with an adjustable seat depth is also provided, along with various methods for operating the different aspects and embodiments of the seating structure.

Abstract: A height adjusting mechanism is connected between a rigid upright extending upwardly from the seat assembly and an inner shell of the back assembly. The height adjusting mechanism includes a ratcheting latch which engages a vertically elongate rack to maintain the back assembly at a selected elevation and a release lever or cam which is connected to the catch and automatically disengages the catch from the rack at the upper limit of travel of the back assembly. The release cam continuously contacts the inner shell of the back assembly and is deactivated merely by a short upward shifting of the back assembly which thereby permits the pawl to reengage the rack at any desired elevation. Accordingly, reengagement of the pawl with the rack can be accomplished at any point between the upper and lower limits of travel of the back assembly.

Abstract: A height adjusting mechanism is connected between a rigid upright extending upwardly from the seat assembly and an inner shell of the back assembly. The height adjusting mechanism includes a ratcheting latch which engages a vertically elongate rack to maintain the back assembly at a selected elevation and a release lever or cam which is connected to the catch and automatically disengages the catch from the rack at the upper limit of travel of the back assembly. The release cam continuously contacts the inner shell of the back assembly and is deactivated merely by a short upward shifting of the back assembly which thereby permits the pawl to reengage the rack at any desired elevation. Accordingly, reengagement of the pawl with the rack can be accomplished at any point between the upper and lower limits of travel of the back assembly.

Abstract: A tilt control mechanism for an office chair includes a spring arrangement which permits forward and rearward tilting of the chair while also urging the chair to a normal upright position. The spring arrangement includes front and rear springs which act in combination such that the upward acting forces acting on the chair can be varied during use. The forces being applied by the front spring are adjusted by a side-actuated tension adjustment mechanism which incorporates a wedge block for adjusting the spring forces. Further, the rear springs provide a variable spring force such that the spring force is maximized when in the normal position but is decreased substantially once the chair is fully reclined. This reduction in spring force allows a user to maintain the chair in the fully reclined position with significantly less force than was required to tilt the chair rearwardly while a sufficient spring force continues to be applied by the front spring to urge the chair to the normal position.

Abstract: A tilt control mechanism for an office chair includes a spring arrangement which permits forward and rearward tilting of the chair while also urging the chair to a normal upright position. The spring arrangement includes front and rear springs which act in combination such that the upward acting forces acting on the chair can be varied during use. The forces being applied by the front spring are adjusted by a side-actuated tension adjustment mechanism which incorporates a wedge block for adjusting the spring forces. Further, the rear springs provide a variable spring force such that the spring force is maximized when in the normal position but is decreased substantially once the chair is fully reclined. This reduction in spring force allows a user to maintain the chair in the fully reclined position with significantly less force than was required to tilt the chair rearwardly while a sufficient spring force continues to be applied by the front spring to urge the chair to the normal position.

Abstract: A tilt control mechanism for an office chair includes a spring arrangement which permits forward and rearward tilting of the chair while also urging the chair to a normal upright position. The spring arrangement includes front and rear springs which act in combination such that the upward acting forces acting on the chair can be varied during use. The forces being applied by the front spring are adjusted by a side-actuated tension adjustment mechanism which incorporates a wedge block for adjusting the spring forces. Further, the rear springs provide a variable spring force such that the spring force is maximized when in the normal position but is decreased substantially once the chair is fully reclined. This reduction in spring force allows a user to maintain the chair in the fully reclined position with significantly less force than was required to tilt the chair rearwardly while a sufficient spring force continues to be applied by the front spring to urge the chair to the normal position.

Abstract: A tilt control mechanism for an office chair includes a spring arrangement which permits forward and rearward tilting of the chair while also urging the chair to a normal upright position. The spring arrangement includes front and rear springs which act in combination such that the upward acting forces acting on the chair can be varied during use. The forces being applied by the front spring are adjusted by a side-actuated tension adjustment mechanism which incorporates a wedge block for adjusting the spring forces. Further, the rear springs provide a variable spring force such that the spring force is maximized when in the normal position but is decreased substantially once the chair is fully reclined. This reduction in spring force allows a user to maintain the chair in the fully reclined position with significantly less force than was required to tilt the chair rearwardly while a sufficient spring force continues to be applied by the front spring to urge the chair to the normal position.