Browse Prior Art Database

Two-Speed Cam

IP.com Disclosure Number: IPCOM000046707D
Original Publication Date: 1983-Aug-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 2 page(s) / 38K

Publishing Venue

IBM

Related People

Steen, MJ: AUTHOR [+2]

Abstract

The figures show a transducer head assembly 10 which is mounted on a base 11 by a flexure spring element 12 and includes a cam follower 13. The transducer head assembly 10 is biased toward the cam by a compression spring 15. Fig. 1 illustrates a cam 21 used to position the transducer head 14 of a flexible disk drive. With, as an example, 35 track locations on the associated disk, twelve degrees of cam rotation are required for each track position (7Πfor cam rise and 5Πfor track dwell). Accessing from the initial track 0 to the final track 34 of such a device requires 408Πof cam rotation. This can be achieved using an overhang portion 23 as the cam surface exceeds 360Πby the angle. The overhang 23 creates manufacturing problems and also drive-to-drive offtrack problems as the overhanging portion tends to deflect.

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Two-Speed Cam

The figures show a transducer head assembly 10 which is mounted on a base 11 by a flexure spring element 12 and includes a cam follower 13. The transducer head assembly 10 is biased toward the cam by a compression spring 15. Fig. 1 illustrates a cam 21 used to position the transducer head 14 of a flexible disk drive. With, as an example, 35 track locations on the associated disk, twelve degrees of cam rotation are required for each track position (7OE for cam rise and 5OE for track dwell). Accessing from the initial track 0 to the final track 34 of such a device requires 408OE of cam rotation. This can be achieved using an overhang portion 23 as the cam surface exceeds 360OE by the angle. The overhang 23 creates manufacturing problems and also drive-to-drive offtrack problems as the overhanging portion tends to deflect. As the number of tracks increase, the required overhang progressively increases. In Fig. 2, the cam 31 is designed to accommodate an increased number of tracks while reducing total cam rotation. Cam 31 is divided into zones I and II. The cam dwell is the same in both zones. The cam rise in zone I is the minimum that can be achieved without cam undercut. The cam rise in zone II is further reduced because undercut improves as the cam radius increases. The drive ratio between the cam and the driving stepper motor (not shown) and the degrees of rotation per stepper motor are fixed. The number of motor steps required to access track to tr...