Patent Document ID: 5563678
Application ID: 08449074
Patent Status: 1

Claim One:
1. A focus detection device for a photo-optical system, the photo-optical system defining an image field and an optical axis, the device comprising: a first focus detection area being provided on the image field of the photo-optical system, without containing an intersection of the image field and the optical axis, and also being provided tangentially oriented with respect to concentric circles centered at the intersection; a second focus detection area being provided on the image field, without containing the intersection, and also being provided radially oriented with respect to concentric circles centered at the intersection; first focus detection means for detecting the focus adjustment condition of the photo-optical system in the first focus detection area using a pair of light rays that pass through the photo-optical system; second focus detection means for detecting the focus adjustment condition of the photo-optical system in the second focus detection area using another pair of light rays that pass through the photo-optical system; and control means for causing the focus detecting of the first focus detection means to have priority over the focus detecting of the second focus detection means and for detecting the focus adjustment condition of the photo-optical system in the first focus detection area.