| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem of a conventional portable telephone set that wastes current consumption for lighting its display section because the display section and an operation section is kept lighting even during a voice speech and a user cannot see the display during the voice speech. SOLUTION: The portable telephone set of this invention determines a sound pressure value or an amplitude value from a signal through microphone input or a signal received from a speech opposite party, compares the value with a preset threshold and decides that the portable telephone set is under voice communication when the value is higher than the threshold. Or, the portable telephone set applies spectral analysis to both the signals and decides that the portable telephone set is under voice communication when the spectrum includes a spectrum denoting the characteristic of a human voice. When the voice speech state is decided, the portable telephone set stops lighting of the display section and the operation section or turns off the display section. |
