| 摘要 |
PROBLEM TO BE SOLVED: To suppress a reduction in the quantity of light of a light source when turning off a transistor while suppressing a surge current.SOLUTION: A bypass circuit 4 has a transistor 41 connected in parallel with a second light source block 52, and applies a current to the transistor 41 to bypass the second light source block 52 and turn off the second light source block 52. When a second switch 12 is turned off to turn off the second light source block 52, the bypass circuit 4 maintains a control signal to the transistor 41 at a first set voltage V1 to operate the transistor 41 in an active region for a first period until a predetermined time passes. After the first period ends, the bypass circuit 4 changes the control signal to the transistor 41 to a second set voltage V2 higher than the first set voltage V1 to operate the transistor 41 in a saturation region. |
