Patent ID: 6208811
Filing Date: 2001-03-27
Classification: G02B

Abstract:
An automatic focussing system comprising:an objective lens having a focussing lens unit;focus detecting means for detecting focus deviation of said objective lens;memory means for storing focus correction data based on focussing characteristics of said objective lens, said focus correction data including a reference value and a factor related to a magnitude of focus deviation;first operation means for calculating a coefficient of movement in accordance with said focus correction data and a non-linear function of the focus deviation detected by said focus detecting means for a magnitude of focus adjustment;second operation means for determining a magnitude of focus adjustment in accordance with said coefficient of movement and said detected focus deviation, wherein said magnitude of focus adjustment is effective to reduce focus deviation to within a predetermined limit irrespective of said detected focus deviation; anddrive means for driving said focussing lens unit in accordance with the determined magnitude of focus adjustment.