Detecting rotational direction of a rotating article

摘要

Method and apparatus for determining the rotational direction of a rotatable article, such as a spindle motor used in a data storage device to rotate a data recording disc. The article includes an index mark which is detected by an index sensor to identify an index reference position on the article. The index sensor and index mark are further used to detect the direction of rotation of the article. In some embodiments, a second sensor is provided so that first and second timing pulses are generated from the index mark by the index sensor and the second sensor. In other embodiments, a second (detection) mark is added to the article so that first and second timing pulses are generated by the index sensor. In either case, a rotational direction detection circuit determines the rotational direction of the article in relation to the first and second timing pulses.