Apparatus for measuring vibration characteristic of head gimbal assembly

Abstract

An apparatus surely measures the vibration characteristic of a head gimbal assembly and has a wide range of resonance frequencies to be set, the apparatus has a first laser Doppler vibrometer to detect a vibration velocity of a shaker, a second laser Doppler vibrometer to detect a vibration velocity of a head of the head gimbal assembly fixed to a fixture, and a reflection mirror to orthogonally reflect a laser beam emitted from the first laser Doppler vibrometer toward the fixture fixed to the shaker, and the apparatus finds the vibration characteristic of the head gimbal assembly according to the detected vibration velocities.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing an apparatus for measuring the vibration characteristic of a head gimbal assembly according to a first embodiment of the present invention;

FIG. 2 is an exploded perspective view showing a fixture according to the first embodiment;

FIG. 3 is a perspective view showing a fastened state of the fixture of FIG. 2;

FIG. 4 is a table showing calculated resonance frequencies of fixtures according to various embodiments of the present invention;

FIG. 5A is a graph showing a frequency-gain curve measured from the fixture of FIG. 3;

FIG. 5B is a graph showing a frequency-phase curve measured from the fixture of FIG. 3;

FIG. 6 is a perspective view showing a fixture according to a second embodiment of the present invention;

FIG. 7 is an exploded perspective view showing a fixture according to a third embodiment of the present invention;

FIG. 8 is a perspective view showing a fastened state of the fixture of FIG. 7;

FIG. 9A is a graph showing a frequency-gain curve measured from the fixture of FIG. 8;

FIG. 9B is a graph showing a frequency-phase curve measured from the fixture of FIG. 8;

FIG. 9C is a graph showing frequency-gain curves measured from a head gimbal assembly;

FIG. 9D is a graph showing frequency-phase curves measured from the head gimbal assembly;

FIG. 10 is a perspective view showing a fixture according to a fourth embodiment of the present invention;

FIG. 11A is a graph showing a frequency-gain curve measured from the fixture of FIG. 10;

FIG. 11B is a graph showing a frequency-phase curve measured from the fixture of FIG. 10;

FIG. 12 is a table showing materials usable for a fixture and masses of the materials according to a fifth embodiment of the present invention;

FIG. 13 is a table showing materials usable for a fixture and the masses and resonance frequencies of the materials in various modes according to the fifth embodiment; and

FIG. 14 is a perspective view showing a fixture according to a related art.

Claims

1. An apparatus for measuring the vibration characteristic of a head gimbal assembly, comprising: a shaker configured to shake the head gimbal assembly;a fixture configured to fix the head gimbal assembly to the shaker;a first laser Doppler vibrometer configured to detect a vibration velocity of the shaker; anda second laser Doppler vibrometer configured to detect a vibration velocity of a head of the head gimbal assembly,the apparatus finding the vibration characteristic of the head gimbal assembly according to the detected vibration velocities.

2. The apparatus of claim 1, wherein the fixture comprises: a base block fixed to the shaker and having an external thread;a mount block having a through hole and joined to the base block with the external thread of the base block being passed through the through hole, the mount block supporting the head gimbal assembly; anda nut fastened to the external thread that protrudes from the mount block, to fix the mount block and base block together.

3. The apparatus of claim 1, wherein the fixture comprises: a base block fixed to the shaker and having an internal thread;a mount block having a through hole and joined to the base block so that the through hole agrees with the internal thread, the mount block supporting the head gimbal assembly; anda bolt passed through the through hole of the mount block and fastened to the internal thread of the base block, to fix the mount block and base block together.

4. The apparatus of claim 2, wherein: the base block has one of a rectangular parallelepiped shape and a cylindrical shape.

5. The apparatus of claim 3, wherein: the base block has one of a rectangular parallelepiped shape and a cylindrical shape.

6. The apparatus of claim 2, wherein: the mount block has a rectangular sectional shape to reduce the total length of the fixture.

7. The apparatus of claim 3, wherein: the mount block has a rectangular sectional shape to reduce the total length of the fixture.

8. The apparatus of claim 2, wherein: at least one of the base block and mount block is made of one of light metal and light alloy.

9. The apparatus of claim 3, wherein: one of the base block, mount block, and bolt is made of one of light metal and light alloy.