| 摘要 |
PROBLEM TO BE SOLVED: To prolong a lighting time period without changing a capacity of an accumulator battery.SOLUTION: A power storage part 430 stores a power supplied from an external power supply 250. A conversion part 440 converts the power stored in the power storage part 430 into a power for lighting a light source of a light source part 460, and supplies the converted power to the light source. From the start of service interruption to the lapse of a reference time period, the power converted by the conversion part 440 is continuously supplied to the light source to continuously lighten the light source. After the lapse of the reference time period from the start of service interruption, the power to be supplied to the light source is periodically changed to periodically change lighting brightness of the light source. |
