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Hard Disk Drive Spindle Motor Excitation Function

IP.com Disclosure Number: IPCOM000035890D
Original Publication Date: 1989-Aug-01
Included in the Prior Art Database: 2005-Jan-28
Document File: 2 page(s) / 75K

Publishing Venue

IBM

Related People

Yamamoto, S: AUTHOR

Abstract

Disclosed is a method which eliminates head-disk interface "stucks" in a hard disk drive. The method comprises the step of switching on/off a spindle motor for driving disks at the natural frequency of the system which consists of a head suspension, and heads and disks which are stuck. By this switching, a resonant vibration occurs in the system and the extra force acts to unstick the head-disk interfaces. (Image Omitted)

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Hard Disk Drive Spindle Motor Excitation Function

Disclosed is a method which eliminates head-disk interface "stucks" in a hard disk drive. The method comprises the step of switching on/off a spindle motor for driving disks at the natural frequency of the system which consists of a head suspension, and heads and disks which are stuck. By this switching, a resonant vibration occurs in the system and the extra force acts to unstick the head-disk interfaces.

(Image Omitted)

Fig. 1 is a block diagram of the system which realizes this method. A motor on/off signal is controlled by a MPU (microprocessor unit). The motor on/off signal is generated when the hard disk drive starts and the motor cannot rotate due to the stick condition of the head-disk. The natural frequency of the stuck system depends on the number of heads which are stuck. To cover all combinations of stuck- head numbers, the motor switching frequency is swept from one stuck- head frequency to the maximum number of stuck head frequencies. Fig. 2 shows one example of the frequencies which are swept.

Fig. 3 shows one example of the effect of this method. In this case, one head is stuck at a landing zone (which is located at the most inner side of a disk). Value A is the spindle motor starting torque, and value B is the peak torque which is produced by this vibration function. As seen in Fig. 3, a force can be obtained which is about 7 times that of a static motor torque.

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