Endoscope apparatus producing video signals from imaging signals at illuminating and non-illuminating periods

Abstract

A CCD for imaging a subject is driven by a CCD driving circuit. An observation image of the subject obtained by the CCD being driven becomes an output signal of the CCD and is converted into a digital signal by an A/D converter through a preprocessing circuit including an amplifying circuit, low-pass filter and sample hold circuit. While the signal of the observation image converted by the A/D converter when the subject is illuminated is stored in a first memory, the signal of the observation image when the subject is not illuminated is stored in the second memory. The signals stored in the first memory and the second memory are instantaneously read and supplied to a subtracting circuit. In the subtracting circuit, operation process for extracting a signal in which an imaging signal during non-illumination is subtracted from an imaging signal during illumination is carried out. The extracted signal is converted into an analog signal by a D/A converter to supply the signal to a video processing circuit, and then, a standard video signal is produced.

Dependencies are inferred from the claim text.