| 摘要 |
PROBLEM TO BE SOLVED: To sufficiently suppress generation of arc jump.SOLUTION: In an alternating current of an approximately rectangular wave, a period in which a duty ratio exceeds 50[%] and is below 100[%], is defined as a period A, a period in which the duty ratio exceeds 0[%] and is below 50[%] is defined as a period B and a period in which the duty ratio is 50[%] is defined as a period C. One alternating current cycle in the period C is smaller than either in the period A and the period B, a sum of an average of the duty ratios in each of terms included in the period A and an average of duty ratios in each of terms included in the period B is equal to 100[%], and a length of the period A is equal to a length of the period B. In a constant light-on state, the periods are shifted in the order of A, C, B, C and this is repeated. |
