Mobile phone

1. A mobile phone including a main unit, a first wireless transmission module, a first input interface and a battery cover, the first input interface being formed on a front side of the main unit, the battery cover being formed on a rear side of the main unit, the mobile phone comprising:

the battery cover having a second input interface facing to an inner wall formed on the rear side of the main unit and a second wireless transmission module, wherein the second input interface is capable of transmitting/receiving a wireless signal to/from the first wireless transmission module of the main unit via the second wireless transmission module when the battery cover is detached from the main unit.

2. The mobile phone according to claim 1 , further comprising a switch circuit for switching an operation mode between the first input interface and second input interface.

3. The mobile phone according to claim 1 , wherein the battery cover further comprises a power source module for supplying power to operate the second input interface.

4. The mobile phone according to claim 3 , wherein the power source module includes a charge circuit and a rechargeable battery coupled electrically to the charge circuit for charging the rechargeable battery.

5. The mobile phone according to claim 1 , wherein the first input interface is capable of inputting numerals.

6. The mobile phone according to claim 1 , wherein the second input interface is capable of inputting of words and characters.

7. A battery cover of a mobile phone, which includes a main unit having a rear side, the battery cover comprising:

an input interface disposed on and facing an inner wall formed on the rear side of the main unit; and

a wireless transmission module;

wherein the input interface is capable of operating thereon, and the wireless transmission module is capable of conducting wireless communication between the battery cover and the mobile phone when the battery cover is detached from the mobile phone.

8. The battery cover according to claim 7 , further comprising a power source module for supplying power to operate the input interface.

9. The battery cover according to claim 8 , wherein the power source module includes a charge circuit and a rechargeable battery coupled electrically to the charge circuit for charging the rechargeable battery.

10. The battery cover according to claim 7 , wherein the input interface is a keypad.

11. The battery cover according to claim 7 , wherein the input interface is a touch screen.