| 摘要 |
An illumination apparatus includes a power supply, a detection unit, a PWM unit, a constant current circuit and an illumination unit. The detection unit detects the brightness of the ambient light and generates a detecting signal according to the brightness of the ambient light. The PWM unit outputs a pulse voltage according to the detecting signal. The constant current circuit supplies a constant current to the illumination unit. The illumination unit emits light according to the pulse voltage. When the brightness of the ambient light is increased, the magnitude of the detecting signal increases and the duty cycle of the pulse voltage increases. The luminous intensity of the illumination apparatus increases. When the brightness of the ambient light is decreased, the magnitude of the detecting signal decreases and the duty cycle of the pulse voltage decreases. The luminous intensity of the illumination apparatus decreases.
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