Dynamic magnetic information storage or retrieval – Automatic control of a recorder mechanism – Controlling the head
Reexamination Certificate
1998-08-24
2001-05-08
Sniezek, Andrew L. (Department: 2651)
Dynamic magnetic information storage or retrieval
Automatic control of a recorder mechanism
Controlling the head
C073S865900, C324S212000, C324S262000
Reexamination Certificate
active
06229664
ABSTRACT:
TECHNICAL FIELD
This invention relates to head-disk interface testers, also called “spin stands,” for testing the head-disk interfaces of magnetic recording disk drives.
BACKGROUND OF THE INVENTION
Head disk interface testers are used in the design and manufacturing of magnetic recording disk drives. Such testers typically include a spindle motor with a removable chuck or clamp that allows a magnetic recording disk to be installed, and an actuator on to which the suspension and magnetic recording head are mounted. The actuator can move the head in a programmed pattern, which may represent a typical seek a pattern during operation of the disk drive, or can maintain the head over a particular region of the disk. The tester is thus able to simulate the operation of the disk drive and enables various mechanical properties of the interface to be determined, including wear of the head and disk, fly height of the slider and “stiction,” or static friction which causes the head to stick to the disk. Conventional head disk interface testers use a linear or rotary stepper motor as the actuator. The stepper motor actuator cannot accurately represent the operation of modern disk drives that use a rotary voice coil motor actuator because, unlike actual disk drives, the stepper motor actuator moves in discrete steps and thus represents a relatively jerky motion of the slider across the disk surface. Many modern disk drives use a load/unload ramp located at the other periphery of the disk to support the suspension and head off the disk surface when the disk drive is not operating. The actuator is required to move the suspension up the ramp for loading and down the ramp for unloading with a smooth continuous motion and with a velocity that may vary according to a specific velocity profile. Because of the jerky motion of stepper motors it is difficult for conventional head disk interface testers to precisely simulate the operation of disk drives during the load/unload function.
What is needed is a head-disk interface tester that can accurately simulate the operation of modern disk drives, including providing continuous motion of the sliders over the disk surfaces and up and down load/unload ramps according to various velocity profiles.
SUMMARY OF THE INVENTION
The invention is a head-disk interface tester that uses a rotary voice coil motor (VCM) actuator and a rotating laser beam that rotates with the actuator to accurately move the head to the desired position and with the desired velocity. A diode laser is located on the rotating actuator and directs a laser beam through the pivot axis of the actuator. The laser beam is received by a linear position detector. The detector provides position data which is used by control circuitry to move the actuator to the position determined by the user or according to a velocity determined by the user. The rotary VCM actuator is mounted on an adjustable stage that allows the height of the actuator to be varied, as well as the distance between the actuator pivot axis and the spindle motor rotation axis to be varied. The VCM actuator is also removable from its mount so that it can be repositioned to locate the head on either side of the disk center to enable the tester to simulate the head-disk interface of both top and bottom disk surfaces. The tester includes an adjustable load/unload ramp, which together with the preselected velocity mode of operation, allows accurate simulation of a wide range of disk drives that load and unload their heads on ramps with a specific velocity.
For a fuller understanding of the nature and advantages of the present invention, reference should be made to the following detailed description taken together with the accompanying figures.
REFERENCES:
patent: 4516177 (1985-05-01), Moon et al.
patent: 5227625 (1993-07-01), Hetzler
patent: 5268801 (1993-12-01), Hazel et al.
patent: 5465182 (1995-11-01), Ishikawa
patent: 5774295 (1998-06-01), Tsai
Albrecht Thomas Robert
Kuan Jenn-Huei Jeffrey
Berthold Thomas R.
Habermehl James L
International Business Machines - Corporation
Sniezek Andrew L.
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