Title:
EVALUATING METHOD OF DEGREE OF FLATNESS OF MAGNETIC DISK
Document Type and Number:
Japanese Patent JPH03137506
Kind Code:
A
Abstract:
PURPOSE:To measure the degree of flatness of a magnetic disk by measuring the amplitude of a harmonic frequency component of a rotational frequency of a plane-vibration waveform of the disk in rotation. CONSTITUTION:A magnetic disk 1 to be measured, a rotary spindle 2 and a magnetic disk fixing metal fitting 3 composed of a spacer ring (a), a clamp metal fitting (b), etc. are provided. A detection signal of a noncontact-type distance sensor 4 is calibrated in a signal processing circuit 5 and further it is subjected to nonlinear correction by the sensor and inputted to a frequency analyzing device 6. A signal of a rotational base angle sensor 7 provided at the rotary spindle 2 is inputted also to the frequency analyzing device 6. The result of analysis of the analyzing device 6 can be obtained on a display with respect to a rotational frequency component, higher components such as secondary and tertiary harmonics and also a vibration component of the magnetic disk not having so much relation with the rotational frequency of the spindle.
Inventors:
YAMAUCHI HIDEO
Application Number:
JP27491189A
Publication Date:
June 12, 1991
Filing Date:
October 24, 1989
Export Citation:
Assignee:
ASAHI GLASS CO LTD
International Classes:
G01B21/30; G11B5/84; G11B20/14; (IPC1-7): G01B21/30; G11B5/84; G11B20/14
Attorney, Agent or Firm:
Shigeo Tsugamura (1 outside)