Patent ID: 7149908

Claim:
A control method of a data transmission apparatus, said apparatus including: a plurality of interface sections, each converting a data into a predetermined transmitting format and transmitting it to an external device; a power source section that supplies electric power to the respective interface sections; and detection sections, each detecting whether or not each of the interface sections is in a connecting state with respect to the external device, said control method comprising the step of: controlling the electric power such that the electric power is supplied to all of the interface sections from the power source section when the detection sections detect that at least one interface section is in a connecting state, and such that no electric power is supplied to the interface sections from the power source section when the detection sections detect that none of the interface sections is in a connecting state, wherein: when the detection sections detect that an interface section is in a connecting state when transmitting a data to the external device via the interface section, the data is controlled so as to be outputted to the interface section, and when the detection sections detect that the interface section is not in a connecting state, a signal is controlled so as to be outputted to the interface section, the signal causing the output of the interface section to be a fixed level.