Sliding mechanism and portable electronic device using the same

A portable electronic device, comprising:

• a base having a keypad section configured therein;
• a sliding cover longitudinally slidably connected to the base to shield or expose the keypad;
• and
• a sliding mechanism, comprising:
• a first plate defining a sliding slot and a control slot, the sliding slot and the control slot forming a predetermined angle therebetween and communicating with each other;
• a second plate longitudinally slidably connected to the first plate, the second plate including a sliding member formed on a surface thereof facing the first plate, the sliding member engaging with the sliding slot and including a positioning assembly, when the sliding member being near one end of the sliding slot and communicating with the control slot, a portion of the positioning assembly being inserted into the control slot to retain the first plate and second plate in a fixed relative position;
• a control assembly slidably received in the control slot;
• and
• a main elastic member, one end of the main elastic member being fixed to one end of the sliding slot, the other end being fixed with the sliding member;
• when the positioning assembly being compressed by the control assembly, the main elastic member providing a force to make the sliding member slide automatically to the other end of the sliding slot.