DIMMER, LIGHTING DEVICE, AND ILLUMINATION CONTROL SYSTEM

PROBLEM TO BE SOLVED: To supply power necessary for stable operation of a lighting device while transmitting a dimming signal through a power line. SOLUTION: A bidirectional thyristor T54 (a switching element) is interposed in the power line 811 for supplying AC power to the lighting device 300. A zero cross detection circuit 120 detects a zero cross of a voltage of the AC power supply AC. A switch control circuit 140 provides: a dimming degree instruction period in which a period for making conductive the bidirectional thyristor T54 and a period for insulating the bidirectional thyristor T54 are included in one half cycle period; and a power supply period in which the bidirectional thyristor T54 continues to be made conductive during the one half cycle period. COPYRIGHT: (C)2010,JPO&INPIT