Patent ID: 7258663

Claim:
An endoscope system comprising: an endoscope having one or more solid-state imaging devices, each solid-state imaging device comprising a charge multiplication mechanism for varying a sensitivity by varying a charge multiplication rate in accordance with the number of pulses or amplitude of the pulses provided to the one or more solid-state imaging devices; a signal processing unit for processing an output signal from the one or more solid-state imaging devices; a light source unit for selectively irradiating first light to perform ordinary light observation and second light to perform special light observation to an object; an observation mode switching device for switching between the ordinary light observation by the first light and the special light observation by the second light; and a sensitivity control device for controlling the charge multiplication rate by varying the number of pulses or the amplitude of the pulses provided to the one or more solid-state imaging devices so that a level of the output signal from the one or more solid-state imaging devices may be a predetermined level; and, an automatic gain control circuit for amplifying an output signal from the one or more solid-state imaging devices so that the level of the output signal becomes said predetermined level when the level of the output signal is less than said predetermined level, wherein the sensitivity control device varies the charge multiplication rate of the one or more solid-state imaging devices depending upon whether the first light is irradiated to the object or the second light is irradiated to the object.