VELOCITY SENSOR AND SEMICONDUCTOR EXPOSURE DEVICE TO WHICH THIS SENSOR IS APPLIED

摘要

PURPOSE:To attain a velocity sensor which can detect velocity precisely even in a low velocity range. CONSTITUTION:A velocity detecting element 601 of a velocity sensor 1 is equipped with a movable minute piece 61 which is so supported as to be rotatable around the center of gravity and generates a frictional force being proportional to the velocity of a fluid and with two electrodes 62 and 62 for detecting a position, two capacitance detecting circuits 631 and 632 and a differential amplifier 64 which make up a shift amount detecting means which outputs an output voltage VOUT1 being proportional to the amount of shift of the movable minute piece 61 around the center of gravity. Moreover, an electrode 65 for driving and a voltage amplifier 66 which make up a means for giving the movable minute piece 61 a holding force proportional to the output voltage VOUT1 and holding it, and a square computation circuit 67 which is a velocity signal calculating means for calculating a velocity signal S1 from the output voltage VOUT1, are provided.