Device for controlling an amount of light of a lighting unit for an endoscope

摘要

A device for controlling an amount of light of a lighting unit for use in an endoscope, used to view an image of an object. The device includes a light shield for shielding light generated by a light source and transmitted to the endoscope. A stepping motor drives the light shield for a series of predetermined time intervals. Brightness of the image is detected during each of the time intervals and a predetermined number of pulses are generated during each of the time intervals. An angular position of the light shielding system is determined and the phase of excitation of the motor is varied in response to the angular position. The pulses generated are used to drive the stepping motor in each of the plurality of time intervals.