An angular velocity sensor is disclosed having a sensing element and a pair of driven mass drive elements. The floating diffusion region is formed having a first doped region and a second doped region which has a higher concentration of dopants than the first doped region. Efficient thermal and electrical conductivity between semiconductor device and heat sink are achieved also by metallic interconnection such as soldering intermediate the semiconductor device and the heat sink. On the contrary, the battery is not charged any more when the temperature of the battery is between the first threshold temperature and the second threshold temperature and the electric quantity of the battery is higher than the first threshold voltage or a first capacity. The photo-electric conversion unit is configured to convert the single-wavelength optical signals to single-wavelength electrical signals.