| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To improve usability capable of automatically changing a brightness lower limit with an incidence state of outdoor light, such as daylight, reducing the adverse effects on feedback control due to the incidence of the outdoor light, and without requiring a troublesome setting process by a user in a lighting device. <P>SOLUTION: The lighting device 1 is equipped with a lighting load section 2, an illuminance sensor part 3, a control part 4 and a memory part 5. The control part 4 processes a feedback control for the illuminance of an illuminated surface 40 by changing light control levels of an illumination load 21 in a specified change range, based on the signal from the illuminance sensor part 2. The control part 4 controls the light control level to be a lower brightness limit due to the incidence of external light, so that when the light control level is kept, as it is, for a fixed time interval, the lower brightness limit is automatically changed to a value of 1.5 times that of the light control lower limit, for example; and the light control level is controlled to increase until the altered lower brightness limit. Accordingly, required illuminance is assured. <P>COPYRIGHT: (C)2007,JPO&INPIT</p> |
