Patent ID: 6018440
Filing Date: 2000-01-25
Classification: G11B

Abstract:
A position detection unit for use in a magnetic disk drive to detect a current position of a magnetic head which is used for recording/reproducing data to/from a magnetic disk medium loaded in said magnetic disk drive, said magnetic disk drive having a main frame having a main surface, a carriage for supporting said magnetic head with a space left between said carriage and the main surface of said main frame, a linear motor for moving said carriage along a predetermined radial direction, and a substrate mounted on said main frame, said position detection unit comprising:a scale mounted on said carriage at a side opposed to the main surface of said main frame, said scale extending along both of a direction in parallel with said predetermined radial direction and a plane perpendicular to the main surface of said main frame, said scale having a plurality of first light transmission/shield elements which are equally spaced along the direction in parallel with the predetermined radial direction and which are used for detecting a current position of the carriage, and said scale having a second light transmission/shield element which is positioned to detect both of a most outer circumference track and an alignment adjusting track of the magnetic disk medium; anda photointerrupter mounted on said substrate and including a light-emitting unit and a light-receiving unit which are opposed to each other with said scale put therebetween, said light-emitting unit having a first light-emitting section located at a position corresponding to the first light transmission/shield elements and a second light-emitting section located at a position corresponding to the second light transmission/shield element, and said light-receiving unit having a first light-receiving section located at a position corresponding to the first light transmission/shield elements and a second light-receiving section located at a position corresponding to the second light transmission/shield element.