A backrest height adjusting device includes a fixing seat fixed in relation to a chair seat and having at least one fixing post. A backrest includes at least one coupling sleeve coupled with the at least one fixing post. At least one gear is rotatably mounted to the fixing block fixed on the backrest and is coupled with a plurality of positioning grooves on the at least one fixing post. An elastic element biases a movable block to move relative to the fixing block in a vertical direction and biases the movable block to mesh with the at least one gear to retain the backrest in a selected height relative to the fixing seat. The movable block is actuatable to disengage from the plurality of teeth of the at least one gear to thereby permit the backrest to move in the vertical direction relative to the fixing seat.

In an aspect, provided is an adjustable telescoping assembly. The adjustable telescoping assembly comprises a first support member and a second support member that is slidable upon the first support member and which defines an interior volume. At least one damping element is provided that extends from outside the second support member, through the second support member into the interior volume and engages the first support member.

An adjustable lifting structure for a chair back contains: a first adjustment unit and a second adjustment unit. The first adjustment unit mates with the second adjustment unit via a transmission cable, and the first adjustment unit includes a longitudinally hollow chamber for slidably accommodating a guide plate connected on a seat. The first adjustment unit includes a body and two covering assemblies. A drive block includes a locking space, a slit, two deformable chambers, a trough, and two projections. The guide plate includes a conducting element and a rail having multiple teeth and multiple cutouts. The second adjustment unit includes an adjuster, an operation cavity, a first aperture, a connecting room, and two stop segments. A transmission cable includes a first transmitting segment and a second transmitting segment, wherein the first transmitting segment has a first defining portion, and the second transmitting segment has a second defining portion.

An adjustable lifting structure for a chair back contains: a first adjustment unit and a second adjustment unit. The first adjustment unit mates with the second adjustment unit via a transmission cable, and the first adjustment unit includes a longitudinally hollow chamber for slidably accommodating a guide plate connected on a seat. The first adjustment unit includes a body and two covering assemblies. A drive block includes a locking space, a slit, two deformable chambers, a trough, and two projections. The guide plate includes a conducting element and a rail having multiple teeth and multiple cutouts. The second adjustment unit includes an adjuster, an operation cavity, a first aperture, a connecting room, and two stop segments. A transmission cable includes a first transmitting segment and a second transmitting segment, wherein the first transmitting segment has a first defining portion, and the second transmitting segment has a second defining portion.

A cushion (1) whose configuration can be varied is constituted by a cushion element (10) inside which there is a fixed frame (20), which covers a lower section (13) of said cushion element (10), and two movable frames (25A), (25B), symmetrical, hinged above said fixed frame (20) and adapted to be comprised within an upper section (14) of the cushion element (10) itself. The movable frames (25 A), (25B) can swing up to 180 independently of one another, for aligning a respective portion (14A), (14B) of said upper section (14) from an external horizontal position (HE) to an internal horizontal position (HI), passing through a vertical neutral position (N) in which the same portion (14A), (14B) is substantially aligned with said lower section (13). In a sofa (D) or an armchair (P) in which the backrest (100) and the armrests (110) are defined by respective cushions (1), many possible configurations of the same are possible, in order to offer maximum seating comfort.

A chair assembly (1) of a chair or an armchair comprises a seat body (2), a backrest body (6), a locking and adjustment device (4), and a backrest support (10). The backrest support (10) is engaged with an articulated parallelogram that allows the position of the backrest body (6) to be changed while keeping it parallel to itself. The backrest support (10) further comprises spring return means.

A chair for providing support to a user's spine to improve posture and for providing ways for the user to perform exercises. The chair may include a flexible connection that enables a back support to move side to side through a sidebending range of motion of the user. The back support, which may include a flexible chair spine, may be configured to adapt to the curvature of the user's spine when the user is seated in the chair. A seat of the chair may include channels and vents to improve air circulation within the seat.

An adjustable height, covered, foldable, configurable modifiable seat with a seat frame (comprising a bottom frame, a back frame, and an upper frame) and at least one frame opening defined by the contours of at least a portion of the seat frame. A bleacher hook is disposed on the seat frame. Lower hinges connect the bottom frame to the back frame and upper hinges connect the back frame to the upper frame. The lower and upper hinges can be locked to provide the frame with stability. A first support member is connected to the lower hinges and a second support member is connected to the upper hinges. A fabric is disposed over at least a portion of said seat frame and at least one frame opening. The modifiable seat is used by a user in a first, second, third, or fourth configuration.

An office chair that is ergonomically configured to allow for the coordination of stretches to the pectoralis minor muscle, trapezius muscle, and scalene muscles to open up the thoracic outlet, release muscle tension, and reinforce proper structure is provided. The stretches may be performed by an average human user while sitting in the office chair throughout the workday. The ergonomically configured chair assembly may have a brace supported by the seatback and extending downwardly therefrom over a left and right shoulder of the seated average human in a cantilevered fashion and an arm restraining device positioned rearward with respect to the rear face of the upstanding seat back.

A chair has a seat, a backrest, a lift structure, a back supporting structure, and a waist supporting structure. The backrest is deposited behind the seat. The lift structure is deposited on the backrest. The back supporting structure has a bending element and multiple supporting strips. The bending element is connected with the backrest and the lift structure, and is elastic and bendable to deform. The supporting strips are deposited on the bending element at spaced intervals from a top to a bottom of the bending element. The waist supporting structure is deposited in front of the back supporting structure. The waist supporting structure has two pivoting bases and a supporting plate. The pivoting bases are deposited on the seat. The supporting plate is pivoted between the two pivoting bases, abuts the back supporting structure, and selectively abuts the backrest.