US Patent 8051537 Hinge assembly

An exemplary hinge assembly includes a rotatable shaft, a rotatable stand, a fixed stand, an elastic member, and a retaining ring. The rotatable stand is non-rotatably connected to the rotatable shaft. The fixed stand and an elastic member are connected to the rotatable shaft. A flange is formed on a proximal end of the rotatable shaft, and a positioning groove is defined in a distal end of the rotatable shaft. The rotatable stand, the fixed stand and the elastic member are positioned between the flange and the positioning groove of the rotatable shaft. The retaining ring engages in the positioning groove of the rotatable shaft, thereby producing an elastic force along the rotatable shaft.