Abstract: The control device includes a seat having a positioning hole. An elevation support connects a first control line and is pivoted to the seat. A control lever has a connecting base received in the receiving room. The connecting base has a receiving hole, a connecting trough and a driving shaft. A tilt support has a through hole and connects a second control line. A cover assembled with the seat has a rotation hole. A rotation support has a cap and a bar. The bar has an insert hole and passes the rotation hole, the through hole and the connecting trough. A bolt passes through the insert hole and the receiving hole.

Abstract: The control device includes a seat having a positioning hole. An elevation support connects a first control line and is pivoted to the seat. A control lever has a connecting base received in the receiving room. The connecting base has a receiving hole, a connecting trough and a driving shaft. A tilt support has a through hole and connects a second control line. A cover assembled with the seat has a rotation hole. A rotation support has a cap and a bar. The bar has an insert hole and passes the rotation hole, the through hole and the connecting trough. A bolt passes through the insert hole and the receiving hole.

Abstract: The adjustment device includes a seat connected to a back by a first rod and an elasticity set. The elasticity has a base connected to the first rod. A pressing rod is connected to the base. A first spring is passed through by the pressing rod and stopped by the base. A pushing block is connected to the pressing rod and the first spring. A rotating rod passes through the seat. Two pressing blocks with a threaded hole are passed by the rotating rod and separately screwed with the rotating rod. Two second springs are passed through by the rotating rod and nipped between the pressing blocks and the edge plates.

Abstract: The armrest assembly includes a connecting seat, an adjusting rod, a link and an armrest seat. The connecting seat has a connecting rod and a hollow connecting tube with a fixing hole. The adjusting rod has a ring and a bar. The bar is received in the connecting tube and formed with adjusting holes in a row. A fixing block is formed under the adjusting holes and inserted into the fixing hole. The link passes through the connecting tube. Two ends of the link are separately formed with a fixing insert for being inserted into one of the adjusting holes and a pushing button. The armrest seat has a support and an armrest. The support is received in the connecting tube and receives the link. The pushing button projects from a through hole of the support.

Abstract: A fold-down tablet used in a chair is disclosed. The tablet includes a board, a torsion positioning mechanism, a shaft and an armrest. The torsion positioning mechanism is fixed to a side of the board for horizontally rotating and positioning the board. The shaft has a protrudent positioning bar and is fixed to the torsion positioning mechanism for making the board vertically rotatable. The armrest has a shaft hole for rotatably receiving the shaft and a slot communicating with the shaft hole. When the board is turned horizontally, the positioning bar is embedded into the slot to be restricted.

Abstract: A fold-down tablet used in a chair is disclosed. The tablet includes a board, a torsion positioning mechanism, a shaft and an armrest. The torsion positioning mechanism is fixed to a side of the board for horizontally rotating and positioning the board. The shaft has a protrudent positioning bar and is fixed to the torsion positioning mechanism for making the board vertically rotatable. The armrest has a shaft hole for rotatably receiving the shaft and a slot communicating with the shaft hole. When the board is turned horizontally, the positioning bar is embedded into the slot to be restricted.