METHOD AND DEVICE OF GENERATING INDEX SIGNAL, DISC DRIVE, AND DD MOTOR

摘要

PROBLEM TO BE SOLVED: To provide a method of generating an index signal capable of obtaining robust and stable generating timing relative to the temperature characteristic of a Hall element. SOLUTION: A magnet 2 whose two poles are polarized without single pole polarization is used for index detection. The magnet 2 is disposed so that the south pole and the north pole may be aligned circumferentially on a rotor 1, and the Hall element 3 is provided at a prescribed position on the radial outside of the rotor 1. When the pole passing in front of the Hall element 3 changes from the north pole to the south pole, a zero cross point occurs at a Hall output signal. The zero cross point is constant independent of temperature. The index signal is generated based on the zero cross point. Thus, it is possible to generate the index signal at stable timing.