| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a dimming control device making stable operations of dimming control where a number of fluorescent lamps are used as the load such as lighting system for a building using a simple configuration with generation of flicker or the like precluded. SOLUTION: A dimming control device is configured so that a load control circuit 4 is installed in series to a fluorescent lamp load 2 consisting of a plurality of fluorescent lamp devices. A controlling means 6 emits a control signal S1 to a transistor TR2 for driving in the circuit 4 and performs a switch-leg control so that the fluorescent lamp load current flowing in a transistor TR1 for switching via the transistor TR2 is shut off for a requisite duration in half the cyclic period. The lightness is set by varying the starting point or width of shutting-off using a variable resistor VR1, etc., of a setting part 5. For example in the case of automatic dimming control in accordance with the ambient light, a CPU 62 emits a control signal S1 with the requisite starting point or width set so that the lightness sensed by an ambient light sensing part 71 becomes the lightness preset by the variable resistor VR1. Accordingly the lightness of fluorescent lamps is suppressed automatically when the arrangement is surrounded by much external light.</p> |
