Patent ID: 6911820

Claim:
A phase detection device, comprising: a first phase detector having a first detecting section for detecting a phase of an object, and a first binarization section for binarizing the phase which said first detecting section has detected by setting hysteresis; a second phase detector having a second detecting section for detecting a phase of the object in a phase different from said first phase detector, and a second binarization section for binarizing the phase which said second detecting section has detected by setting the hysteresis; a power supply section having an always energized mode for always supplying a power to said first phase detector and said second phase detector, and an intermittent energized mode for intermittently supplying the power to said first phase detector and said second phase detector; and a control section for, in said always energized mode, when detection phases of said first phase detector and/or said second phase detector do not change for more than a predetermined time, making the power supply section shift to said intermittent energized mode, and in said intermittent energized mode, storing the detection phases of said first phase detector and said second phase detector just before shifting to said intermittent energized mode from said always energized mode, and when both the detection phases of said first phase detector and said second phase detector change from the stored detection phases of said first phase detector and said second phase detector, changing the power supply section from said intermittent energized mode to said always energized mode.