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Flexible dummyhead for de-pop actuator transfer function improvement

IP.com Disclosure Number: IPCOM000013507D
Original Publication Date: 2000-Feb-01
Included in the Prior Art Database: 2003-Jun-18
Document File: 4 page(s) / 281K

Publishing Venue

IBM

Abstract

This invention is a method to solve the resonance problem by changing the rigidity of dummyheads

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Flexible dummyhead for de-pop actuator transfer function improvement

This invention is a method to solve the resonance problem by changing the rigidity of dummyheads

of

HDD's. So far, dummyheads are designed just for balancing the de-pop actuator and adjusting the inertia.

The transfer function of dummyhead itself is different from that of HGA, so high frequency resonance of

de-pop actuator and full head actuator become different. Sometimes it causes de-pop actuator unique

resonance problem.

We found that we can solve that kind of resonance problem by changing the rigidity of dummyheads. In developing 3inch, 10000rpm HDD, we had the resonance problem on the de-pop actuator. End arm mode in 8kHz caused the instability of servo loop and PZT loop for the active damping. We tried to change the rigidity of dummyhead by changing it's profile. Fig.1, Fig2 are normal dummyhead and flexible dummyhead. Flexible dummyhead has the same sway mode frequency with HGA. Fig.3 - 5 are the transfer function of full head actuator, de-pop actuator with normal dummyheads, and de-pop actuator with flexible dummyheads, simulated by I-DEAS FEM analysis. They shows that flexible dummyhead is effective in reducing the high peak gain that only de-pop actuator has, and making the transfer function similar to that of full head actuator.

Fig.1 Normal dummyhead

1

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Fig.2 Flexible dummyhead

Frequency response function

Frequency (Hz)

0

-180

-360

-66.27

-70.00

-80.00

-90....