Mobile terminal device capable of more effectively utilizing operation portions, conductive portion, operation detecting unit, power supply unit, and signal processing unit

A mobile terminal device, comprising:

• a body;
• operation portions provided to the body;
• a conductive portion provided to the body, an electrical state of the conductive portion changing in response to an operation on the operation portions;
• an operation detecting unit that is connected to the conductive portion, and detects an operation on the operation portions based on change in the electrical state of the conductive portion;
• a power supply unit connected to the conductive portion;
• a signal processing unit that is connected to the power supply unit and processes a signal resonated by the conductive portion;
• a switching unit that switches connection of each of the conductive portions and the power supply unit;
• a circuit board on which the plurality of conductive portions are disposed;
• and
• a proximity state detecting unit that detects a proximity state of a physical object relative to each of the operation portions,
• wherein the conductive portion comprises a signal line that electrically connects the operation portions and the operation detecting unit,
• wherein the signal line transfers a signal indicating an operation is performed to the operation portions,
• wherein the signal line is connected to the power supply unit and operates as an antenna element,
• wherein a plurality of the operation portions are provided,
• wherein a plurality of the conductive portions are provided correspondingly to the plurality of operation portions,
• wherein each of the plurality of conductive portions functions as an antenna, and
• wherein, when one operation portion among the plurality of operation portions is operated, the switching unit selectively connects the conductive portions other than a conductive portion corresponding to the one operation portion thus operated to the power supply unit based on the proximity state.