| 摘要 |
PROBLEM TO BE SOLVED: To prolong the service life of a battery by providing a box formed in a can shape with a power saving means for making the power supply of the battery in an off-state excepting for during the communication of a portable telephone set housed together with the battery power source. SOLUTION: Hands-free telephony equipment is provided with a box formed in a can shape and in this box, a telephone set housing part is formed for inserting a portable telephone set 2. This telephone set 2 is provided with a power saving means 19 for turning on a battery 14 only during communication and turning off the battery 14 in the other case. This power saving means 19 is composed of an antenna 191, a detection circuit 192 as a detecting means, an amplifier circuit 193 as a switching means, a frequency/voltage converting circuit 194, a comparator circuit 195 and a switching circuit 196. The antenna 191 detects noises generated by receiving a telephone call through the portable telephone set 2 to operate it. |
