Control circuit for video endoscope

摘要

Disclosed is a control circuit which is connected to a video endoscope, having a CCD in the distal end thereof. The control circuit supplies driving clock pulses to the CCD, and converts a picture element signal pulses from the CCD into a continuous image signal, by clamping, or sampling and holding, the signal pulses. The converted signals are further subjected to video processing. A scope discrimination resistor is contained in the endoscope, in the vicinity of a connector thereof, which connects the endoscope and the control circuit. The resistance value of the resistor depends on the length of the endoscope. When the endoscope is connected to the control circuit, the resistor is connected in series with a constantcurrent source in a scope discrimination circuit. The discrimination circuit discriminates the scope length by detecting the resistance value of the resistor as a terminal voltage. The waveform of the driving clock pulses for the CCD is modified in accordance with the result of the discrimination, and the timing for clamping, or sampling and holding, the picture-element signal pulses from the CCD (10), is determined by the discrimination result.