Dimmer

A dimmer, comprising:

• a pair of input terminals that is electrically connected between a load configured to be lit and an AC power supply;
• a bidirectional switch that is configured to be switched so as to conduct and interrupt a bidirectional current between the pair of input terminals;
• an input device that is configured to receive a dimming level representing a value of light output of the load;
• and
• a controller configured to control the bidirectional switch according to the dimming level,
• the controller controlling the bidirectional switch to keep the bidirectional switch in an off-state from a start point of a half cycle of the AC voltage of the AC power supply to a first time point when a first time period therefrom elapses, and to turn the bidirectional switch to an on-state at the first time point,
• the controller also controlling to turn the bidirectional switch to the off-state at a second time point when a second time period elapses from the first time point,
• the controller further controlling the bidirectional switch to keep the bidirectional switch in the off-state from the second time point to an end point of the half cycle.