ENDOSCOPE LIGHT SOURCE DEVICE

PROBLEM TO BE SOLVED: To obtain an endoscope light source device which is capable of preventing the adverse influence by irradiation with excess illumination light at the time of changing over from automatic modulated light to manual modulated light. SOLUTION: The signal corresponding to the brightness of a subject is formed from the image pickup signal by a CCD 33 built in a television camera 11 mounted at the soft endoscope 2. This signal is compared with a reference brightness signal. When the automatic modulated light mode for modulating the light of a discharge lamp 17 by a diaphragm 22 is changed over to the manual modulated light mode in such a manner that the reference brightness may be attained, a CPU 48 limits the opening quantity of the diaphragm 22 by this changeover signal so as to attain the exit light quantity of about half the max. exit light quantity to prevent the irradiation of bio-tissue, etc., with the excess illumination light, by which the occurrence of the adverse influence by the irradiation with the excess illumination light is prevented.