To control a light emitted from a fluorescent lamp having phosphors with
different afterglow properties for different colors, a center of a
lighting control signal for controlling the lighting of the fluorescent
lamp is controlled to constantly align with the center of a Hsync period
so that despite the variation of the lighting time of the fluorescent
lamp, a barycenter of the quantity of light from the fluorescent lamp in
the Hsync period almost aligns with the center of the Hsync period to
reduce the offset of the barycenter.
