Abstract: A chair having a seat and a back rest comprises a fluid-containing cushion in the back rest that provides passive automatically adjustable support for the user's lumbar region. The cushion can comprise one or more fluid-containing chambers encompassing the areas of the user's upper back and lumbar regions. As the user leans backs, fluid is forced from the regions adjacent the upper back down to the lumbar region to provide enhanced lumbar support to the user.

Abstract: An adjustable armrest assembly for a chair includes a mounting member connected to the chair. The mounting member has an upper base. A first horizontal slide element is slidably mounted to the upper base and is adjustably slidable in a first direction with respect to the upper base. The first slide element is restrained after adjustment with respect to the upper base by frictional engagement between the upper base and the first slide element. A second horizontal slide element for slidably mounting to the first slide element is slidable in an arcuate path crossing the first direction. The second slide element is restrained after adjustment with respect to the first slide element by frictional engagement between the second slide element and the first slide element.

Abstract: An adjustable armrest assembly for a chair includes a mounting member connected to the chair. The mounting member has an upper base. A first horizontal slide element is slidably mounted to the upper base and is adjustably slidable in a first direction with respect to the upper base. The first slide element is restrained after adjustment with respect to the upper base by frictional engagement between the upper base and the first slide element. A second horizontal slide element for slidably mounting to the first slide element is slidable in an arcuate path crossing the first direction. The second slide element is restrained after adjustment with respect to the first slide element by frictional engagement between the second slide element and the first slide element.

Abstract: A horizontally adjustable armrest for a chair including a vertically slideable element having a base, a lower horizontal slide element movable longitudinally, an upper horizontal slide element movable laterally and an armrest cover. The lower horizontal slide element includes a longitudinally extending slot with a shoulder. Two fasteners extend through the slot and are fastened to the base. Under the fasteners' heads are springs and washers to bias the lower slide element into frictional engagement with the base. The upper surface of the lower horizontal slide element includes a pair of guide rails which are received in recesses formed in the bottom surface of the upper horizontal slide element. The upper slide element includes two slots extending perpendicular to the slot of the lower slide element. Fasteners, springs and washers are used to bias the upper slide element into frictional engagement with the lower slide element. An armrest cover fits over the horizontal slide elements.

Abstract: A vertically adjustable armrest assembly having a support, a plate fitted to an interior of said support, the plate having a series of vertically aligned openings, a slide having an armrest at a top end portion, and a lateral slot for guiding a block into and out of selective aligned openings in the plate. A rod having a saw tooth portion complementing a slanted opening in the block allows manipulation of the rod to selectively move the block into and out of the plate openings.

Abstract: An adjustable chair scat with a locking mechanism that is torque limiting and resistant to loosening. The chair includes a seat pan, a seat plate, a rotatable fastener and two rings. The seat pan and seat plate have openings for receiving the fastener. The fastener includes a cup handle and a threaded insert. The threaded insert is engaged with the seat pan through an opening in the seat pan while the seat plate is sandwiched between the seat pan and the fastener. When being rotated, the cup handle slips relative to the threaded insert after a predetermined resistance is reached so as to cease the application of torque to the threaded insert. One of the rings is keyed to rotate with the fastener and the other ring is keyed to remain non-rotatable. The first ring includes an array of cantilevered teeth where each tooth has a first surface disposed at a smaller angle from a horizontal reference plane and a second surface which is disposed at a greater angle from the horizontal reference plane.

Abstract: A vertically and horizontally adjustable chair armrest is disclosed. The armrest includes an outer shroud, an upstanding support with a central opening and an armrest base. Within the central opening is a guide tube that moves vertically and has oppositely disposed slots. Within the guide tube, but mounted to rotate only, is a rod. At the lower end of the rod is a locking element that extends through the slots in the guide tube. The rod is rotated by a user pivoted lever bearing down on a spring biased activator nut. The nut is keyed to move only in a linear direction but is threaded to engage a mating thread on the rod, thereby causing the rod to rotate. When the locking element is rotated out of engagement with notches in the support opening, the armrest may be adjusted in a vertical direction. Releasing the lever allows the spring to bias the locking element into engagement with the notches to lock the armrest.

Abstract: A locking device for allowing horizontal seat positioning of a chair seat has a friction strip or brake pad between a seat pan and a seat plate. A screw and spring assembly is used to resiliently hold the seat pan and the seat plate together such that by lifting up on the forward portion of the seat pan, the friction strip, if attached to the seat plate, is separated from the seat pan allowing the seat pan to be moved horizontally in forwardly and rearwardly directions, thus adjusting the seat position. When the front of the seat pan is lifted substantially vertically, the screw and spring assembly is compressed to allow the seat pan to separate sufficiently from the friction strip and allow relative movement of the seat pan with respect to the seat plate. As an alternative, a lever may be used to loosen a locking mechanism and therby allow seat adjustment.

Abstract: An ergonomic chair includes a four-bar linkage arrangement wherein a lower frame member is provided with a rigid front support and a rigid rear support with a seat member pivotably connected to the front support. A back rest has an upper support pivotably connected at an upper end of the rear support of the lower frame member. A link member pivotably connects at a first end to a rear support of the seat member and at second end to a lower support of the back rest. This novel arrangement permits tilting movement of the backrest rearwardly relative to the lower frame member causing elevation of a rear portion of the seat member, permitting the feet to remain on the floor and alleviating pressure on the user's thighs, while rotation occurs closely coincident with the pivot axis of the user's hips and while maintaining a generally uniform gaze line.

Abstract: An adjustable chair seat with a locking mechanism that is torque limiting and resistant to loosening. The chair includes a seat pan, a seat plate, a rotatable fastener and two rings. The seat pan and seat plate have openings for receiving the fastener. The fastener includes a cup handle and a threaded insert. The threaded insert is engaged with the seat pan through an opening in the seat pan while the seat plate is sandwiched between the seat pan and the fastener. When being rotated, the cup handle slips relative to the threaded insert after a predetermined resistance is reached so as to cease the application of torque to the threaded insert. One of the rings is keyed to rotate with the fastener and the other ring is keyed to remain non-rotatable. The first ring includes an array of cantilevered teeth where each tooth has a first surface disposed at a smaller angle from a horizontal reference plane and a second surface which is disposed at a greater angle from the horizontal reference plane.

Abstract: An adjustable chair seat with a locking mechanism is disclosed. The chair includes a seat pan, a seat plate and a torque limiting fastener. The seat pan and seat plate have openings for receiving the fastener which comprises a cup handle and a threaded insert. The threaded insert is engaged with the seat pan through an opening in the seat pan while the seat plate is sandwiched between the seat pan and the fastener. Once engagement is made, the fastener cannot be disengaged; and once a predetermined resistance is reached the cup handle slips relative to the threaded insert so as to cease the application of torque to the threaded insert.

Abstract: A chair back upright tilts about a pivot axis with respect to a chair seat plate and has a protrusion on the bottom portion thereof. When the occupant of a chair reclines, the protrusion on the back upright and a stop plate make contact with each other. The contact stops the tilting of the back upright. A lever handle, fixedly attached to the stop plate, can be rotated thereby providing more or less tilting of the back upright before contact between the protrusion and the stop plate occurs.