Rotation detection device having detector and signal processor

A rotation detection device comprising:

• a detector that is arranged with a predetermined gap with respect to an outer peripheral portion of a rotating body in which rotation position information is periodically provided on the outer peripheral portion at constant intervals, and detects a magnetic change received from the outer peripheral portion as a rotation position of the rotating body changes according to a rotation of the rotating body;
• and
• a signal processor that acquires the rotation position information of the rotating body based on a detection result of the detector, wherein:
• the detector includes a first magnetic element, a second magnetic element, a third magnetic element, a fourth magnetic element and a fifth magnetic element;
• each constant interval is defined as b;
• the first magnetic element and the third magnetic element are arranged with an interval of b in a rotation direction of the rotating body;
• the first magnetic element outputs a first signal;
• the third magnetic element outputs a third signal having a same phase as the first signal;
• the second magnetic element is arranged between the first magnetic element and the third magnetic element in the rotation direction of the rotating body, and outputs a second signal having a phase with respect to the first signal and the third signal and a same period as the rotation position information;
• the fourth magnetic element and the fifth magnetic element are arranged between the first magnetic element and the third magnetic element in the rotation direction of the rotating body;
• the second magnetic element is arranged between the fourth magnetic element and the fifth magnetic element in the rotation direction of the rotating body;
• the signal processor acquires a differential signal between a first calculation signal and a second calculation signal as the rotation position information having the period corresponding to the constant intervals;
• the first calculation signal has a same period as the second signal based on the second signal;
• the second calculation signal has a phase with respect to the first calculation signal based on the first signal and the third signal;
• and
• the signal processor acquires a signal having a phase with respect to the differential signal based on detection results of the fourth magnetic element and the fifth magnetic element, as rotation mode information of the rotating body.