| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a dimmer which controls an LED lighting fixture by a phase control method, in which the light control table can be selected automatically and time and effort of setting is saved, and optimum light control can be made according to the LED composition order voltage in the lighting fixture. <P>SOLUTION: The dimmer comprises a closed circuit in which a two-way switching element Q1 having a self hold function, the lighting fixture 2 using LEDs, and an AC power supply Vs are connected in series, and has a phase control circuit which can change effective power to the lighting fixture 2 by changing the switching-on period of the two-way switching element Q1. The time difference between the zero cross point of the input voltage and the zero cross point of the current flowing in the two-way switching element Q1 is measured, and on the basis of the time difference measured, the light control table, which is the relations between the light control level and the switching-on period of the two-way switching element Q1 is selected. <P>COPYRIGHT: (C)2006,JPO&NCIPI</p> |
