Personal hands-free accessory for mobile device

1. A hands-free accessory for a mobile device, comprising:

a microphone element; and

a telecoil coupled with the microphone element in parallel;

wherein the microphone element and the telecoil are coupled with an output terminal of the hands-free accessory, and

wherein an induced electric current is generated in the telecoil by a magnetic field generated by an electric current flowing in a wire loop outside the hands-free accessory.

2. The hands-free accessory of claim 1 , wherein the output terminal of the hands-free accessory is configured to electrically or wirelessly couple with an input terminal of the mobile device.

3. The hands-free accessory of claim 1 , further comprising:

an ear speaker coupled with an input terminal of the hands-free accessory.

4. The hands-free accessory of claim 3 , wherein the input terminal of the hands-free accessory is configured to electrically or wirelessly couple with an output terminal of the mobile device.

5. The hands-free accessory of claim 1 , further comprising:

a first switch coupled between the microphone element and the telecoil.

6. The hands-free accessory of claim 5 , wherein the first switch is automatically turned on or closed when a telecommunication signal is input or transmitted to the hands-free accessory from the mobile device.

7. The hands-free accessory of claim 1 , wherein the microphone element comprises:

a capacitor element, and

a Field Effect Transistor (FET), wherein

a first end of the capacitor element is coupled with a source terminal of the FET,

a second end of the capacitor element is coupled with a gate terminal of the FET,

a first end of the telecoil is coupled with the source terminal, and

a second end of the telecoil is coupled with a drain terminal of the FET.

8. The hands-free accessory of claim 1 , further comprising:

a capacitor coupled with the telecoil in series, or

a second switch coupled with the telecoil in series, wherein

a first end of the capacitor or a first end of the second switch is coupled with a second end of the telecoil, and

a second end of the capacitor or a second end of the second switch is coupled with the output terminal of the hands-free accessory.

9. The hands-free accessory of claim 8 , wherein the microphone element comprises:

a capacitor element, and

a FET, wherein

a first end of the capacitor element is coupled with a source terminal of the FET,

a second end of the capacitor element is coupled with a gate terminal of the FET,

a first end of the telecoil is coupled with the source terminal, and

the second end of the capacitor or the second end of the second switch is coupled with a drain terminal of the FET.

10. The hands-free accessory of claim 1 , further comprising:

a housing,

wherein the microphone element and the telecoil are in the housing.

11. The hands-free accessory of claim 1 , further comprising:

a shield configured to reduce electric interference between the telecoil and the microphone element.

12. A hands-free accessory, comprising:

a microphone element; and

a telecoil coupled with the microphone element in parallel;

wherein the microphone element and the telecoil are coupled with an output terminal of the hands-free accessory, and

wherein inductance of the telecoil is set according to a predetermined signal-to noise ratio of the telecoil.

13. A mobile device, comprising:

an input terminal configured to couple with an output terminal of a hands-free accessory including a microphone element and a telecoil coupled with the microphone element in parallel;

a bias voltage circuit configured to supply a bias voltage to the microphone element, the bias voltage circuit coupled with the input terminal of the mobile device; and

a processor configured to process a signal input or transmitted to the mobile device from the input terminal of the mobile device.

14. The mobile device of claim 13 , wherein the microphone element comprises a Field Effect Transistor (FET), and the bias voltage is set to operate the FET in the microphone element.

15. The mobile device of claim 13 , further comprising:

a resistor between the bias voltage circuit and the input terminal of the mobile device.

16. The mobile device of claim 13 , further comprising:

a first operational amplifier having a first inverting terminal and a first non-inverting terminal; and

an analog/digital (A/D) converter,

wherein the first inverting terminal is coupled with a ground, and the first non-inverting terminal is coupled with the input terminal of the mobile device, and

wherein an input port of the A/D converter is coupled with a first output terminal of the first operational amplifier, and an output port of the A/D converter is coupled with an input port of the processor.

17. The mobile device of claim 13 , wherein the processor is further configured to control turning on/off or closing/opening of a first switch between the microphone element and the telecoil.

18. The mobile device of claim 13 , further comprising:

a third switch between the bias voltage circuit and a point coupling the bias voltage circuit and the input terminal of the mobile device.

19. The mobile device of claim 18 , wherein the processor is further configured to control turning on/off or closing/opening of the third switch.

20. The mobile device of claim 13 , further comprising:

a digital/analog (D/A) converter; and

a second operational amplifier having a second inverting terminal, a second non-inverting terminal, and a second output terminal,

wherein an input port of the D/A converter is coupled with an output port of the processor, and wherein the second inverting terminal is coupled with a ground, the second non-inverting terminal is coupled with an output port of the D/A converter, and the second output terminal is coupled with an output terminal of the mobile device.