Patent ID: 9602716
Date: 2017-03-21
CPC Classifications: G02B,G03B,H04N

Claim:
1. A focus-detection device comprising: a first detecting unit configured to detect a first phase difference between a first image signal based on a light beam that has passed through a partial region of an exit pupil of an imaging optical system, and a third image signal based on a light beam that has passed through the entire region of the exit pupil; a second detecting unit configured to detect a second phase difference between a second image signal based on a light beam that has passed through another partial region of the exit pupil, and a fourth image signal based on a light beam that has passed through the entire region of the exit pupil; and a computing unit configured to compute a defocus amount of the imaging optical system using a sum of the first phase difference and the second phase difference, wherein the first detecting unit detects the first phase difference while shifting a section of the first image signal with respect to a fixed section of the third image signal in a predetermined direction, and the second detecting unit detects the second phase difference while shifting a section of the second image signal with respect to a fixed section of the fourth image signal in the predetermined direction.