Patent ID: 6225799
Filing Date: 2001-05-01
Classification: G01N,G11B

Abstract:
A method for testing magnetic heads and hard disks, comprising the steps of: providing a tester which has a housing for supporting a spindle motor, that holds at least one magnetic disk for rotation therewith, and a voice coil motor having a voice coil with a pivot arm for supporting at least one magnetic head magnetically interacting with said at least one magnetic disk, and a permanent magnet for interacting with said voice coil; attaching a Hall-effect sensor to said voice coil for interacting with said permanent magnet; testing at least one of test objects selected from a group consisting of said at least one magnetic disk and said at least one magnetic head by utilizing said Hall-effect sensor for positioning said at least one magnetic head in a position required for testing with respect to said at lest one magnetic disk and at the same time for measuring a friction force between said at least one magnetic head and said at least one magnetic disk during rotation of said at least one magnetic disk, said testing being a start-stop testing and prior to starting rotation of said at least one magnetic disk, said at least one magnetic head rests on said at least one magnetic disk for developing a friction force during rotation of said at least one magnetic disk; providing said tester with an instrumental amplifier and voltage-to-current converter; combining said permanent magnet, said Hall-effect sensor, said voice coil, said instrumental amplifier, and said voltage-to-current converter into a close-loop positioning and measuring system; and measuring said friction force in terms of a voltage applied to said voltage-to-current converter during said start-stop testing.