| 摘要 |
PROBLEM TO BE SOLVED: To automatically adjust a whole luminance level of a display part according to a use time and a running position. SOLUTION: Peripheral illuminance (first illuminance) is estimated according to time information based on a time-illuminance function prescribed by an illuminance estimation part 22, and when the running portion is in a non- sunshine region, the peripheral illuminance in the non-sunshine region such as a tunnel, etc., is estimated as second illuminance by a region judgment part 23, and an either darker side between the first illuminance and the second illuminance is comparison selected by a luminance decision part 24, and the luminance level of the display part 1 is decided based on the comparison result. |
