inserted at a back surface of the nut 219 for preventing automatic loosening in the meantime a second embodiment of the present invention will be explained with reference to the attached drawings in which a shape of the frictional elastic member in the first embodiment is modified to be more simpler and an adjusting washer is provided additionally between the rotating bracket and the frictional elastic member for serving as a buffer in a case the frictional elastic member is compressed excessively and adjusting the torque between the rotating bracket and the frictional elastic member fig5 illustrates a perspective partial assembly view of a hinge assembly in accordance with a second preferred embodiment of the present invention and fig6 illustrates a section of key parts of the hinge assembly in fig5 referring to fig5 and 6 the hinge assembly in accordance with a second preferred embodiment of the present invention has components identical to the first embodiment except the frictional elastic member 30 and the adjusting washer 33 the second embodiment may also have a supplementary torsion spring 216 additionally alike the first embodiment the second embodiment hinge assembly includes a fixed bracket 205 coupled to a two stepped cylindrical coupling part 204 of different diameters on each shaft 200 and a frictional elastic member 208 coupled next to the fixed bracket 205 alike the first embodiment a frictional elastic member 208 opened in front and rear direction is made to be inserted into a coupling part 204 and a bottom part of the frictional elastic coupling 204 is formed to fit to the lower step 203 of the coupling part 204 the frictional elastic member 208 has a sloped surface part 31 extended from the bottom part having a diameter decreases continuously as it goes upward and longitudinal grooves.