Abstract: The fastening structure includes an inner sleeve, a quick-release handle and an outer sleeve. The inner sleeve has an outer threaded conic surface, a through slot, shrinkable slots and claw plates between adjacent two of the shrinkable slots. The quick-release handle is provided at a bottom end of the inner sleeve for controlling a width of the through slot. The outer sleeve is used for connecting the footrest ring and has an inner threaded conic surface to screw the outer sleeve onto the inner sleeve.

Abstract: The armrest structure includes a connecting seat having a sleeve. A height adjustment rod is disposed in the sleeve and has two symmetric boards. Each of the boards is formed with recesses. A receiving room is formed between the two boards. An elevation rod is disposed in the sleeve. An end of the elevation rod has a projection received in the receiving room. Another end of the elevation rod has a connecting seat with a cylinder and a spring. An armrest set has a tube and an armrest connected atop the tube. The tube is received in the sleeve and sheathes the height adjustment rod and elevation rod. A top of the tube is formed with a channel for receiving a trigger. A fixing bar passes through the projection and is embedded into one of the recesses.

Abstract: The chair includes a cushion having a chassis, a back and an adjustment structure connected to the chassis. The adjustment structure includes a base frame and a back frame. The base frame has a main body with a connecting arm rotatably connecting the chassis. The back frame is connected between the back and the base frame and has a connecting portion connected to the base frame and a support substantially perpendicularly extending from the connecting portion toward the back. An arc-shaped bend portion is formed between the support and the connecting portion. A top of the support is connected to the back.

Abstract: The invention includes a frame, a back board and an adjustment set. The frame has a central trench and an adjustment board with limiting slots and two sliding slots. The back board is connected to the frame and has an opening. The adjustment set is connected between the frame and the back board and includes: a sliding seat having an engagement block received in the opening, and the engagement block having a recess with a through hole; a limiting body received in the recess, having a central bar in the through hole and an extending portion with a limiting bar in the limiting slots, and a C-shaped trench around the central bar; a torsion spring received in the C-shaped trench, two ends thereof protruding from the C-shaped trench and stopped by the recess; and two sliders received in the sliding slots. The sliders and the sliding seat are fixed to the back board.

Abstract: The fastening structure includes an inner sleeve, a quick-release handle and an outer sleeve. The inner sleeve has an outer threaded conic surface, a through slot, shrinkable slots and claw plates between adjacent two of the shrinkable slots. The quick-release handle is provided at a bottom end of the inner sleeve for controlling a width of the through slot. The outer sleeve is used for connecting the footrest ring and has an inner threaded conic surface to screw the outer sleeve onto the inner sleeve.

Abstract: The invention provides an adjustable footrest ring for a chair with a central post. The invention includes an inner sleeve, a quick-release handle, a support frame and a ring. The inner sleeve is used for being put around the central post and has an outer threaded surface, a through slot and a pair of passing holes below the outer threaded surface. The quick-release handle is formed with a through hole at an end thereof. The through hole corresponds to the passing holes for being passed through by a bolt. The inner sleeve is shrunken when the bolt is tightened and the quick-release handle is closed. The support frame has an outer sleeve and support rods radially extending therefrom. An inner threaded surface is formed inside the outer sleeve so as to screw the outer sleeve onto the inner sleeve. The ring is connected to outer ends of the support rods.

Abstract: The invention provides an adjustable footrest ring for a chair with a central post. The invention includes an inner sleeve, a quick-release handle, a support frame and a ring. The inner sleeve is used for being put around the central post and has an outer threaded surface, a through slot and a pair of passing holes below the outer threaded surface. The quick-release handle is formed with a through hole at an end thereof. The through hole corresponds to the passing holes for being passed through by a bolt. The inner sleeve is shrunken when the bolt is tightened and the quick-release handle is closed. The support frame has an outer sleeve and support rods radially extending therefrom. An inner threaded surface is formed inside the outer sleeve so as to screw the outer sleeve onto the inner sleeve. The ring is connected to outer ends of the support rods.

Abstract: A mechanism fixed under a cushion for adjusting an interval of two armrests is disclosed. The invention includes a base, an armrest support and a handle set. The base is a hollow body with a channel and has an elastic block with a central through hole. The armrest support has a connecting section slidably penetrating the channel. The connecting section is formed with a longitudinal through hole corresponding to the central through hole in position. The handle set is fixed under the base and includes a handle with a fixing bar and an opening; a presser received in the opening and has a fixing hole corresponding to the central through hole in position and an engagement trench for engaging with the fixing bar; and a bolt passing through the fixing hole, longitudinal hole and central through hole, and screwed with a nut to fasten the handle to the base.

Abstract: The chair includes a cushion having a chassis, a back and an adjustment structure connected to the chassis. The adjustment structure includes a base frame and a back frame. The base frame has a main body with a connecting arm rotatably connecting the chassis. The back frame is connected between the back and the base frame and has a connecting portion connected to the base frame and a support substantially perpendicularly extending from the connecting portion toward the back. An arc-shaped bend portion is formed between the support and the connecting portion. A top of the support is connected to the back.

Abstract: The invention includes a frame, a back board and an adjustment set. The frame has a central trench and an adjustment board with limiting slots and two sliding slots. The back board is connected to the frame and has an opening. The adjustment set is connected between the frame and the back board and includes: a sliding seat having an engagement block received in the opening, and the engagement block having a recess with a through hole; a limiting body received in the recess, having a central bar in the through hole and an extending portion with a limiting bar in the limiting slots, and a C-shaped trench around the central bar; a torsion spring received in the C-shaped trench, two ends thereof protruding from the C-shaped trench and stopped by the recess; and two sliders received in the sliding slots. The sliders and the sliding seat are fixed to the back board.

Abstract: A mechanism fixed under a cushion for adjusting an interval of two armrests is disclosed. The invention includes a base, an armrest support and a handle set. The base is a hollow body with a channel and has an elastic block with a central through hole. The armrest support has a connecting section slidably penetrating the channel. The connecting section is formed with a longitudinal through hole corresponding to the central through hole in position. The handle set is fixed under the base and includes a handle with a fixing bar and an opening; a presser received in the opening and has a fixing hole corresponding to the central through hole in position and an engagement trench for engaging with the fixing bar; and a bolt passing through the fixing hole, longitudinal hole and central through hole, and screwed with a nut to fasten the handle to the base.

Abstract: The invention includes a connecting seat having a sleeve. A height adjustment rod is disposed in the sleeve and has two symmetric boards. Each of the boards is formed with recesses. A receiving room is formed between the two boards. An elevation rod is disposed in the sleeve. An end of the elevation rod has a projection received in the receiving room. Another end of the elevation rod has a connecting seat with a cylinder and a spring. An armrest set has a tube and an armrest connected atop the tube. The tube is received in the sleeve and sheathes the height adjustment rod and elevation rod. A top of the tube is formed with a channel for receiving a trigger. A fixing bar passes through the projection and is embedded into one of the recesses.

Abstract: The leg rest includes a base frame and a retractable frame assembly. The base frame has a through hole and two connecting sockets. A connecting rod connects between the connecting sockets. Two hole seats are provided on the connecting rod. The retractable frame assembly connects with the base frame and includes a first support frame having two connecting arms and a main board connected therebetween. The connecting arms separately connect the connecting sockets. A link with a connecting tube perpendicularly extends from the main board. The connecting tube is coaxially connected between the hole seats. A second support frame rotatably connects to the main board. A support seat rotatably connects to the second support frame and has a transversal rod. A vertical rod is perpendicularly connected between the transversal rod and the main board. A support pad is fixed onto the support seat.

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 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.