Signal charge that has accumulated in photodiodes of a photoreceptor area
in a CCD is multiplied by a charge multiplier and then applied to a
floating diffusion amplifier, which has been set to a small conversion
coefficient, or to floating gate amplifier, which has been set to a large
conversion coefficient. If the accumulated amount of signal charge is
small, the charge is converted to a video signal by the floating gate
amplifier having the large conversion coefficient. If the accumulated
amount of signal charge is large, the charge is converted to a video
signal by the floating diffusion amplifier having the small conversion
coefficient. Thus a video signal having a high level is obtained even if
the amount of signal charge is small. Since it is unnecessary to change
driving pulses that are applied to the charge multiplier, the
multiplication factor of the charge multiplier will not fluctuate.