A hinge
assembly (10) for joining a body and a cover of a
mobile phone includes an inner housing (100), a key (110), a pressure spring (120), a can (130), a slider (140), a
damper (150), an outer housing (160), a
fastener (170), and a torsion-bar spring (190). The can includes an
acceptor (132) defining an axial slot (132b) in a
peripheral wall thereof, and a protrusion (131) having a stepped hole. The slider has an adjoining block (141) received in the stepped hole. One end of the torsion-bar spring is secured onto the
fastener, and the other end of the torsion-bar spring is received in the slot. A user presses the key to slidably remove the slider from the stepped hole of the can, whereupon the torsion-bar spring can rotationally drive the slider and the
fastener, with the outer housing turning in
unison therewith. Thus the cover is opened.