Browse Prior Art Database

Head Load/ Unload Stepper Motor Return Spring Mechanism

IP.com Disclosure Number: IPCOM000121625D
Original Publication Date: 1991-Sep-01
Included in the Prior Art Database: 2005-Apr-03
Document File: 2 page(s) / 64K

Publishing Venue

IBM

Related People

Cullom, CD: AUTHOR [+3]

Abstract

Disclosed is a Return Spring Mechanism for a Head Load/Unload stepper motor in a Head/Disk Assembly (HDA).

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Head Load/ Unload Stepper Motor Return Spring Mechanism

      Disclosed is a Return Spring Mechanism for a Head
Load/Unload stepper motor in a Head/Disk Assembly (HDA).

      The Return Spring Mechanism provides a unique means of allowing
tight control of return spring torque as a function of angle.  The
return spring torque overcomes the stepper motor holding torque
during HDA Emergency Power Off and motor controller failure
conditions.  This provides accurate control of the time for stepper
motor rewind and head unload, at a specific spindle RPM and generated
back EMF voltage range.  The spring returns the stepper motor output
shaft to its storage position in a continuous motion, not exceeding
maximum output angular velocity and head unload velocity
specifications.

      The Return Spring Mechanism (Figs. 1 and 2) consists of a
helical extension spring 8, a gear/plate assembly 9, and a fixed
idler roller 10 in the motor gear cup/cover.  The unique arrangement
of components allow both ends of the spring 8 to attach to the plate
16.  The return spring has a swivel hook swaged to a hardened steel
ball.  The ball is captured in the conical end of the spring.  This
configuration allows for smooth rotation and minimized spring wire
wear and fatigue, as the mechanism rotates.  By varying the spring
rate and preload, as well as the Pivot Arm limit pin 17 location, a
broad range of characteristic output torques are available to control
stepper motor head unlo...