| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a device for controlling a signal lamp which controls the luminance of the signal lamp corresponding to peripheral lightness and its method. SOLUTION: This device has an illumination sensor 120, which is located closely to LED signal lamps 51, 52 and 53, for measuring the illumination of peripheral environment light and FET 41, 42 and 43 for switching and controlling a power to be supplied to the signal lamp corresponding to a PWM control signal having a duty ratio to change corresponding to an output from the illumination sensor 120 and the switching means 41, 42 and 43 perform switching to prolong the time of electrification to the signal lamp corresponding to the PWM signal of large duty ratio when the illumination of the peripheral environment light is high and to shorten the time of electrification to the signal lamp corresponding to the PWM signal of small duty ratio when the illumination of the peripheral environment light is low.</p> |
