A lower chair for supporting an upper chair on which a user sits. The lower chair including a base, a swivel mechanism supported by the base and defining a vertical swivel axis, and a four-bar linkage mounted to the swivel mechanism for rotation about the swivel axis. The four-bar linkage includes a coupler link that moves about a coupler curve. The lower chair also includes a column having a lower end affixed to the coupler link for movement of the lower end along the coupler curve. The column defines a column axis and is adapted to support the upper chair.

In a configuration in which a holder holding a controller is mounted on a seat part with a plate-shaped member, the exposure of the mounting part of the plate-shaped member on which the holder is mounted is eliminated. A seat device includes a pressure sensor measuring a value relating to the seated person's state, a vibration imparting device performing a vibration imparting operation, an ECU controlling the vibration imparting device corresponding to the measurement result of the pressure sensor, a holder holding the ECU, and a mounting bracket fixed to a lower frame such that the holder is mounted on the lower frame of a seat part. The mounting bracket includes a mounting projection on which side wall of the holder is mounted in a predetermined mounting direction. When the side wall is mounted on the mounting projection, the mounting projection is covered with the side wall.

In a configuration in which a holder holding a controller is mounted on a seat part with a plate-shaped member, the exposure of the mounting part of the plate-shaped member on which the holder is mounted is eliminated. A seat device includes a pressure sensor measuring a value relating to the seated person's state, a vibration imparting device performing a vibration imparting operation, an ECU controlling the vibration imparting device corresponding to the measurement result of the pressure sensor, a holder holding the ECU, and a mounting bracket fixed to a lower frame such that the holder is mounted on the lower frame of a seat part. The mounting bracket includes a mounting projection on which side wall of the holder is mounted in a predetermined mounting direction. When the side wall is mounted on the mounting projection, the mounting projection is covered with the side wall.

A synchronous-tilt reclining office chair includes a seat, a backrest interconnected to the seat, and an arrangement providing a synchronous-tilt mechanism that controls synchronous movement of the backrest and seat between a normal non-reclined position and a reclined position. Recline tension provided by the arrangement is a function of a force required to compress at least one tensioning spring mounted below the seat, a weight applied on the seat by a seat occupant, and a location of the weight on the seat relative to front and rear portions of the seat, whereby, as the weight is applied toward the front portion of the seat, recline tension is reduced and, as the weight is applied toward the rear portion of the seat, recline tension is increased.

A chair chassis includes: a base, provided with an accommodation chamber; a backrest support; a memory stopper, disposed on the backrest support, wherein the memory stopper is provided with a first arc surface facing the base; a locking slider, slidably disposed in the accommodation chamber of the base, wherein the locking slider is provided with a second arc surface disposed opposite to the first arc surface, and a side of the locking slider is provided with a first rack; a first elastic member; and an elastic slider, slidably disposed in the accommodation chamber of the base, wherein one end of the elastic slider is provided with a second rack, wherein the second rack is meshable with the first rack. Accordingly, the chair chassis according to the embodiments of the present disclosure achieves reclination memory adjustment of a backrest of the chair.

A seating arrangement includes a rigid back frame, a flexible back shell coupled to the back frame and including a pair of vertical side portions and at least two strap portions extending laterally between the side portions and including a forwardly-facing surface configured to support a back of a seated user, the at least two strap portions including a lowermost strap portion, the lowermost strap portion configured to deflect a first distance when a rearwardly-directed force is exerted on the lowermost strap portion by a seated user, and a lumbar assembly supported from the back frame and configured to support the lumbar region of a back of a seated user, the lumbar assembly configured to deflect a second distance when the rearwardly-directed force is exerted on the lumbar assembly by a seated user, wherein the first distance and the second distance are substantially similar.

A chair chassis includes: a base, provided with an accommodation chamber; a backrest support; a memory stopper, disposed on the backrest support, wherein the memory stopper is provided with a first arc surface facing the base; a locking slider, slidably disposed in the accommodation chamber of the base, wherein the locking slider is provided with a second arc surface disposed opposite to the first arc surface, and a side of the locking slider is provided with a first rack; a first elastic member; and an elastic slider, slidably disposed in the accommodation chamber of the base, wherein one end of the elastic slider is provided with a second rack, wherein the second rack is meshable with the first rack. Accordingly, the chair chassis according to the embodiments of the present disclosure achieves reclination memory adjustment of a backrest of the chair.

In a configuration in which a holder holding a controller is mounted on a seat part with a plate-shaped member, the exposure of the mounting part of the plate-shaped member on which the holder is mounted is eliminated. A seat device includes a pressure sensor measuring a value relating to the seated person's state, a vibration imparting device a vibration imparting operation, an ECU controlling the vibration imparting device corresponding to the measurement result of the pressure sensor, a holder holding the ECU, and a mounting bracket fixed to a lower frame such that the holder is mounted on the lower frame of a seat part. The mounting bracket includes a mounting projection on which a side wall of the holder is mounted in a predetermined mounting direction. When the side wall is mounted on the mounting projection, the mounting projection is covered with the side wall.

In a configuration in which a holder holding a controller is mounted on a seat part with a plate-shaped member, the exposure of the mounting part of the plate-shaped member on which the holder is mounted is eliminated. A seat device includes a pressure sensor measuring a value relating to the seated person's state, a vibration imparting device a vibration imparting operation, an ECU controlling the vibration imparting device corresponding to the measurement result of the pressure sensor, a holder holding the ECU, and a mounting bracket fixed to a lower frame such that the holder is mounted on the lower frame of a seat part. The mounting bracket includes a mounting projection on which a side wall of the holder is mounted in a predetermined mounting direction. When the side wall is mounted on the mounting projection, the mounting projection is covered with the side wall.

A chair includes a lower chair and an upper chair. The lower chair includes a tilt-swivel mechanism defining a vertical swivel axis, a yoke, and a column extending between the tilt-swivel mechanism and the yoke. The upper chair is pivotably mounted to the yoke about a horizontal upper chair pivot axis. The upper chair includes a seat adapted to cradle the ischial tuberosities of a user.