Browse Prior Art Database

Disk File Actuator

IP.com Disclosure Number: IPCOM000083029D
Original Publication Date: 1975-Mar-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 3 page(s) / 82K

Publishing Venue

IBM

Related People

Lissner, RW: AUTHOR [+3]

Abstract

A two-stage actuator is used in conjunction with a servo concept in which a two-layer disk contains both servo and data information. The servo information is permanently written directly beneath the data. The servo head and data head are mounted on a common slider, which flies over the disk surface and which is of rigid construction. A sector servo approach can also be used.

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Disk File Actuator

A two-stage actuator is used in conjunction with a servo concept in which a two-layer disk contains both servo and data information. The servo information is permanently written directly beneath the data. The servo head and data head are mounted on a common slider, which flies over the disk surface and which is of rigid construction. A sector servo approach can also be used.

The two-stage actuator is composed of a coarse linear actuator and a fine rotary actuator (Fig. 1). The coarse actuator can be either a standard voice coil motor 10, a linear stepping motor design, or any other linear actuator. The fine actuator or "piggyback" actuator 12 consists of the following components:.

(a) A light-weight pivot arm 14 supports a magnetic head 16 on one end and a flat rectangular coil 18 on the other (Fig. 2).

(b) A flexural pivot 20 provides the rotational axis.

(c) A shielded magnetic core mounted to ground is cantilevered between the disks. The core has a slit gap 24 in which is suspended the flat rectangular coil
18. The magnetic structure is segmented into discrete magnets 26a,b with alternating polarity. In the gaps 22 of adjacent magnets lie the two driving legs of the rectangular coil 18.

During operation, the carriage holding the fine actuator 12 is coarse positioned causing the rectangular coil 18 to move linearly in the core slit. The coil is prevented from generating current by solid-state circuitry or by opening the circuit. After reaching final coarse position, current is applied to the coil 18 causing the arm 14 to pivot.

In the piggyback (P.B.) actuator 12, the armature is not attached nor has a fixed positional relationship to the magnetic circuit. The magnetic circuit which provides the working gap is fixed in place, hence, is not part of the first-stage actuator moving mass.

The basic magnetic circuit for a P.B. actuator 12 is shown in Fig. 3 and consists...