PROBLEM TO BE SOLVED: To provide an electronic endoscope system capable of capturing a subject image which is illuminated by any illumination light with correct exposure in observing the subject using the illumination lights with different characteristics.SOLUTION: An electronic endoscope system is composed of: a light source unit for alternately repeating irradiation and non-irradiation of an illumination light, and alternately switching the illumination light to be irradiated between a first illumination light and a second illumination light different from the first illumination light in at least one of light volume and spectral characteristics an imaging device for imaging a subject illuminated with the illumination light and imaging device control means for reading out electric charge accumulated by the imaging device during an irradiation period of the illumination light during a non-irradiation period of the illumination light following the irradiation period. In this composition, according to at least one of the difference in light volume and the difference in spectral characteristics between the first illumination light and the second illumination light, the irradiation period of the first illumination light and the irradiation period of the second illumination light are set to different lengths.SELECTED DRAWING: Figure 5COPYRIGHT: (C)2017,JPO&INPIT【課題】特性の異なる照明光を使用して被写体を観察する場合に、何れの照明光で照明された被写体像も適正露出で撮影可能な電子内視鏡システムを提供する。【解決手段】電子内視鏡システムを、照明光の照射と非照射とを交互に繰り返し、且つ照射する照明光を、第1の照明光と、光量及び分光特性の少なくとも一方が第1の照明光と異なる第2の照明光と、の間で交互に切り替える光源部と、照明光により照明された被写体を撮像する撮像素子と、照明光の照射期間中に撮像素子にて蓄積された電荷を、照射期間に続く照明光の非照射期間中に読み出す撮像素子制御手段とから構成する。この構成において、第1の照明光と第2の照明光との光量差及び分光特性の違いの少なくとも一方に応じて、第1の照明光の照射期間と第2の照明光の照射期間とが異なる長さに設定する。【選択図】図5
