| 摘要 |
Provided is a radio-controlled wristwatch capable of determining whether or not the illuminance of light irradiating a solar cell is high on the basis of a plurality of different criteria without directly measuring an output voltage value or an output current value of the solar cell. The radio-controlled wristwatch includes: a solar cell; a control circuit which stops operation under a predetermined condition; and an illuminance detection circuit which outputs a signal indicating whether or not illuminance of light irradiating the solar cell is higher than a given threshold value. The radio-controlled wristwatch switches the given threshold value between a first illuminance threshold value and a second illuminance threshold value that is larger than the first illuminance threshold value, starts the control circuit in a stop state when a signal indicating that the illuminance is higher than the first illuminance threshold value is output, receives a satellite signal containing time information from a satellite when a signal indicating that the illuminance is higher than the second illuminance threshold value is output, and displays time corresponding to the time information contained in the received satellite signal. |
