Abstract: A chair waist backrest height adjusting device includes a chair backrest bracket above the backrest, a worm rotated by turning the adjusting rod to slightly lower position, a first gear that is engaged with it and a second gear that is coaxially rotated with the first gear, and the chair backrest bracket under the backrest is provided with a waist backrest that can be slid up and down. The back of the waist backrest is provided with a tooth-row that is engaged with the second gear, so that the seated person on the chair can stretch out one or two hands to the adjustment rod for the forward or reverse turning operation, and the waist backrest can easily drive the waist backrest up and down, further the waist backrest is more easily adjusted, and there will be no displacement in the adjusted waist backrest.

Abstract: A desktop device for lifting and lowering a keyboard and monitor includes: a vertically-movable stand-unit fixed to a bottom-base and having a securing outer-pipe and a vertically-movable inner-pipe penetratingly fitted therein; a monitor-holder and a keyboard-supporting plate both disposed at the vertically-movable inner-pipe; a control unit having a slide control-key and mounted on the keyboard-supporting plate; and a pneumatic rod with an extensible rod having one end. A gas-releasing pin is disposed at the end of the extensible rod, and the pneumatic rod received in the vertically-movable inner-pipe. The top of the pneumatic rod is pivotally fixed to the top of the vertically-movable inner-pipe, allowing another end of the pneumatic rod to connect with a connector pivotally fixed to the bottom-base. A slide control-key is disposed at the keyboard-supporting plate and connected to a control-cable which is pulled and released to press on and release the gas-releasing pin.

Abstract: An omnidirectional adjustment-oriented positioning device of an office chair armrest includes two parallel inner links pivotally connected between an armrest rotation fixing unit and a rotation base. The inner links are enclosed in outer links to form a parallel four-link swing link component. The rotation base is axially disposed at a pad. An armrest component capable of horizontal rotation and displacement is disposed at the armrest rotation fixing unit. Inner and external wheel components with bevel gears meshing with each other are disposed between upper ends of the outer links and the armrest rotation fixing unit. Positioning gears which mesh with each other are disposed at the armrest rotation fixing unit. A positioning wheel is mounted at the armrest rotation fixing unit and rotatable such that a rotation component for rotating the inner wheel component abuts against the inner wheel component and thus drives the positioning wheel to move outward.