Photographing light quantity controller for endoscope

Abstract

A photographing light quantity controller for an endoscope, which is used to control the quantity of illuminating light when a photograph is to taken through the endoscope. The controller includes a device for photoelectrically converting a brightness level of the reflected light from an object, which is illuminated with a light source, into an electric signal and outputting the signal; a device for integrating an output from the photoelectric conversion device and outputting an integral state value; a device for differentially detecting and outputting the rise of a signal representative of an integral state value which is outputted from the integration device; and a device for controlling the brightness of illuminating light in such a manner that, when the output from the differentially detecting device is greater than a first reference value, the brightness of light that illuminates the object is reduced, whereas, when the output from the differentially detecting device is less than a second reference value which is smaller than the first reference value, the brightness of the illuminating light is increased, and when the output from the differentially detecting device is between the first and second reference value, the brightness of the illuminating light is controlled to a predetermined level between the two brightness levels.