Abstract: An armrest for a chair includes a lower bushing, an upper bushing, and a resilient ring shaped part received in the lower bushing. An engaging portion is formed on an end of the lower bushing, and a side surface of the lower bushing defines a toothed rack hole, a plurality of teeth are formed at two opposite sides of the toothed rack hole. The upper bushing nests the lower bushing therein and defines a through hole corresponding to the toothed rack hole. A supporting is formed on an end of the upper bushing differing from the end of the upper bushing adjacent to the engaging portion. A button opposite to the through hole in the upper bushing is formed on the resilient ring shaped part and protrudes to an outer of the upper bushing from the toothed rack hole and the through hole. An H shaped latching portion is formed on the button and engages with the teeth of the lower bushing.

Abstract: An armrest for a chair includes a lower bushing, an upper bushing, and a resilient ring shaped part received in the lower bushing. An engaging portion is formed on an end of the lower bushing, and a side surface of the lower bushing defines a toothed rack hole, a plurality of teeth are formed at two opposite sides of the toothed rack hole. The upper bushing nests the lower bushing therein and defines a through hole corresponding to the toothed rack hole. A supporting is formed on an end of the upper bushing differing from the end of the upper bushing adjacent to the engaging portion. A button opposite to the through hole in the upper bushing is formed on the resilient ring shaped part and protrudes to an outer of the upper bushing from the toothed rack hole and the through hole. An H shaped latching portion is formed on the button and engages with the teeth of the lower bushing.

Abstract: A stepless adjustable supporting device includes a base, a lifting arm, a transmission wheel assembly and an elastic module. The present invention employs the lever principle that the product of the load force and the load force arm is equal to the product of the applied force and the applied force arm. Further, with the structure in which a transmission wheel of the transmission wheel assembly is configured to have an eccentric groove, the applied torque generated by the supported article such as displayer with respect to the supporting device is kept to be equal to the load torque generated by the supporting device. In this way, the supporting device can perform a stepless adjustment of various heights while exhibit a supporting effect.