| 摘要 |
PROBLEM TO BE SOLVED: To provide a hands-free unit that can avoid a troublesome charging operation when the capacity of a battery of a portable telephone set is decreased during a hands-free speech. SOLUTION: The hands-free unit 10 connected to a portable telephone set 20 with a cable 18 for a hands-free speech is provided with a charging section 13 that charges a battery 21 of the portable telephone set 20 through the cable 18. The portable telephone set 20 can make a hands-free speech with a sufficient battery capacity of the portable telephone set 20 by providing a charging function to the hands-free unit 10 in this way. Furthermore, in order to prevent occurrence of a noise in a received sound during the hands-free speech, the hands-free unit 10 inhibits charging during the hands-free speech in the case that the charging section 13 is configured to employ a constant voltage power supply or is configured to employ a constant current power supply. |
