Patent ID: 9609204
Date: 2017-03-28
CPC Classifications: G02B,G03B,H04N

Claim:
1. An auto-focus device comprising: a focusing target area setting section that sets a focusing target area to be brought into focus in an imaging area; a phase difference AF section that outputs a first focusing evaluation value signal, which indicates an amount of defocus, on the basis of an output signal which is obtained from one phase difference imaging element which forms a plurality of subject images, into which light incident through a focus lens is divided through a pupil division, on an imaging surface; an optical path length difference AF section that outputs a second focusing evaluation value signal, which indicates an amount of defocus, on the basis of respective output signals of a first imaging element and a second imaging element which are disposed at positions where optical path lengths are different from each other in optical paths of light incident through the focus lens; a focusing position estimation section that estimates a focusing position on the basis of at least one of the first focusing evaluation value signal and the second focusing evaluation value signal; a focus lens position detection section that detects a position of the focus lens; a focus lens position evaluation section that calculates a difference between the position of the focus lens and the focusing position estimated by said focusing position estimation section; an AF switching section that sets, as a focusing evaluation value signal, the first focusing evaluation value signal which is output from said phase difference AF section on the basis of an output signal obtained from a center portion of the phase difference imaging element, when the difference between the position of the focus lens and the estimated focusing position is greater than a first threshold value, sets, as a focusing evaluation value signal, the first focusing evaluation value signal which is output from said phase difference AF section on the basis of an output signal obtained from the focusing target area of the phase difference imaging element, when the difference is greater than a second threshold value and is equal to or less than the first threshold value, and sets, as a focusing evaluation value signal, the second focusing evaluation value signal which is output to said optical path length difference AF section on the basis of output signals obtained from the focusing target areas of the first imaging element and the second imaging element, when the difference is equal to or less than the second threshold value; and a focus lens movement control section that moves the focus lens on the basis of the focusing evaluation value signal which is output in said AF switching section.