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Dummyhead re-arrangement for solving actuator resonance problem

IP.com Disclosure Number: IPCOM000013910D
Original Publication Date: 2000-Feb-01
Included in the Prior Art Database: 2003-Jun-19
Document File: 2 page(s) / 148K

Publishing Venue

IBM

Abstract

This invention is a method to solve the resonance problem by re-arranging dummyheads of de-pop actuator of HDDs. 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

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Dummyhead re-arrangement for solving actuator resonance problem

This invention is a method to solve the resonance problem by re-arranging dummyheads of de-pop

actuator of HDDs. 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 number, the weight, and the position 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 two types of new dummyhead arrangement as follows.

HD # 6HD Trial 1 Trial 2

11 Dummyhead No Dummyhead No Dummyhead

10 Dummyhead 2x weight Dummyhead x 1.5 weight Dummyhead

9 Dummyhead Dummyhead x 1.5 weight Dummyhead

8 Dummyhead Dummyhead x 1.5 weight Dummyhead

7 HGA HGA HGA

6 HGA HGA HGA

5 HGA HGA HGA

4 HGA HGA HGA

3 HGA HGA HGA

2 HGA HGA HGA

1 Dummyhead 2x weight Dummyhead x 1.5 weight Dummyhead

0 Dummyhead No Dummyhead No Dummyhead

The following graph shows the difference of the transfer functions between normal 6hd actuator and the actuator with trail 1 arrangement. End arm mode frequency changed from 8kHz to over 11kHz, and it's gain become lower. Trial 2 arr...