Heat roller having improved coupling structure to prevent slip of a roller cap for fixing apparatus

A heat roller for a fixing apparatus, comprising:

• a conductive cylindrical roller pipe;
• an induction coil housed in the conductive cylindrical roller pipe;
• an internal expanding pipe installed in the conductive cylindrical roller pipe which presses the induction coil toward the conductive cylindrical roller pipe;
• a gear coupled to an end of the internal expanding pipe and provided with a first electrode which supplies a current to the induction coil;
• an end cap coupled to an other end of the roller pipe and provided with a second electrode;
• and
• a coupling unit which prevents the end cap from slipping in relation to the internal expanding pipe in an axial or rotational direction of the internal expanding pipe.

A heat roller for a fixing apparatus, comprising:

• a roller pipe;
• a resistive heat element housed in the roller pipe;
• an internal expanding pipe housed in the roller pipe which presses the resistive heat element against the roller pipe;
• and
• a locking unit which forces the internal expanding pipe against the roller pipe and thereby prevents the resistive heat element from twisting.