AUTOMATIC FOCUSING DEVICE

摘要

PROBLEM TO BE SOLVED: To provide an automatic focusing device capable of detecting a focusing point at appropriate speed in practical use by shortening time required to stabilize a liquid crystal lens when acquiring a plurality of focus signals. SOLUTION: The automatic focusing device includes: the liquid crystal lenses (1 and 7) whose focal distances are changed according to applied voltage; a first electrode 20 and a second electrode 22 provided at different positions on the liquid crystal lenses (1 and 7); a liquid crystal lens driving means 6 for applying predetermined voltage to the liquid crystal lenses (1 and 7) through the respective electrodes (20 and 22); a photoelectric conversion means 3 for generating an image signal from an optical image transmitted through the liquid crystal lenses (1 and 7); and a control means 5 for controlling the liquid crystal lens driving means 6 to fix voltage applied to either of the electrodes (20 and 22) and increase voltage applied to the other while extracting the plurality of focus signals by sampling the generated image signal from the photoelectric conversion means 3, and controlling the liquid crystal lens driving means 6 so that the focus signal may be maximum based on the plurality of focus signals. COPYRIGHT: (C)2008,JPO&INPIT