| 摘要 |
<p>PURPOSE: To give the visual comfortableness by maintaining the illuminance of the working surface nearly constant without lowering the workability. CONSTITUTION: The signal having the fluctuation characteristic at l/f output from a 1/f fluctuation generating filter circuit 3 is converted to the dimming signal by a signal converting circuit 4. Switching elements Q1 , Q2 are triggered on the basis of this dimming signal so as to put on light sources 61 , 62 . The signal converting circuit 4 performs the dimming so that the frequency spectrum of the quantity of light of the light sources 61 , 62 to be changed with the lapse of time is inversely proportional to the frequency, and lights the light sources 61 , 62 with the fluctuation at 1/f. The light sources 63 , 64 are lighted by the signal having the fluctuation characteristic at 1/f, which is supplied to the signal converting circuit 4 through a subtraction circuit 5. Change of the quantity of light of the fluctuation at 1/f of one pair of light sources 61 , 62 and change of the quantity of light of the fluctuation at 1/f of the other pair of light sources 62 , 64 are combined together so as to obtain the nearly constant quantity of light as the whole.</p> |
