Patent ID: 7911526

Claim:
An automatic focusing apparatus comprising: a liquid crystal lens which forms a refractive index profile; an optical-to-electrical conversion unit which converts an optical image focused through said liquid crystal lens into an electrical signal and outputs said electrical signal as an image signal; a focus signal extracting unit which causes said refractive index profile to change by applying a first range of voltage to said liquid crystal lens, and extracts a plurality of focus signals based on said image signal; a focusing point identifying unit which identifies a focus signal corresponding to a focusing point from among said plurality of extracted focus signals; a focusing point adjusting unit which adjusts the focusing point by applying to said liquid crystal lens a second voltage that is capable of generating the refractive index profile corresponding to the focus signal identified by said focusing point identifying unit and that is smaller than said first range of voltage applied to said liquid crystal lens in order to obtain the focus signal identified by said focusing point identifying unit; and a storage unit which stores said first range of voltage and said second voltage corresponding to each individual voltage in said first range of voltage by establishing an association therebetween.