Protective cover, key assembly using the same and portable electronic device using the key assembly

A portable electronic device, comprising:

• a housing;
• a battery cover detachably mounted to the housing and defining a key hole through the battery cover;
• a circuit board assembled within the housing;
• and
• a key assembly comprising:
• a key assembled to the battery cover and received within the key hole, the key comprising a key body and a resisting block protruding, from the key body;
• a switch module assembled to the housing corresponding to the key and electrically connecting with the circuit board, the switch module being configured to be triggered by the key;
• and
• a protective cover assembled to the housing for covering the switch module, the protective cover comprising a cover body and a pressing body, the cover body having an accommodating cavity recessed therefrom and an accommodating hole defined through a base wall of the accommodating cavity;
• the pressing body comprising a pressing portion and a resisting post protruding from the pressing portion, the pressing portion being received within the accommodating cavity and exposed from the accommodating hole;
• an elastic sheet mounted with the key, the elastic sheet comprising an elastic arm extending therefrom and a throe through hole defined through the elastic arm;
• the key fixed to the elastic arm with the resisting block of the key passing through the corresponding through hole and abutting against the pressing portion;
• wherein when the key is pressed toward the switch, the resisting block together with the elastic arm is moved toward the switch to resist against the pressing portion for triggering the switch to generate an electric control circuit for controlling the portable electronic device as the battery cover is mounted to the housing.