Rotational positioner latch for a magnetic disc storage

Details Rotational positioner latch for a magnetic disc storage Rotational positioner latch for a magnetic disc storage

1991-03-18

1992-05-26

Psitos, Aristolelis

Dynamic magnetic information storage or retrieval

Record transport with head stationary during transducing

Drum record

360106, 360 9801, 360137, G11B 554, G11B 2122

Patent

active

051173182

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

The invention is directed to a rotational positioning means for a magnetic disc storage and, in particular, to a positioner for a magnetic disc storage including magnetic heads carried on a swivel member movable via a drive system and including a latch for blocking movement of the swivel member in an idle position.
Positioning means fashioned as rotational positioners have prevailed in magnetic disc storages, particularly given 51/4 and 31/2 stores. Rotational positioners have a swivelling part that is seated rotationally movable on a positioning axis arranged parallel to the axis of a disc pack. This swivelling part comprises a plurality of swivel arms carrying magnetic heads and comprises carrier arms lying roughly opposite these swivel arms with respect to the positioning axis. These carrier arms carry either a coil that is deflected relative to stationary permanent magnets or a magnet, whereby the excited magnetic coil is then rigidly arranged. In the former instance, the rotational positioner is referred to as a swivel coil positioner; in the latter, it is referred to as magnetic armature positioner. The two types of rotational positioner are inherently equivalent. Leaving the structural differences out of consideration, the coil in combination with the permanent magnet or magnets shall be referred to below as a magnetic drive system of the rotational positioner.
Such rotational positioners are known, for example, from IEEE Transactions on Magnetics, Vol. MAG-17, No. 4, July 1981, pages 1392 ff or from Electronics, 21 April 1982, pages 181 ff. During ongoing operation, the magnetic heads, gliding on an air cushion, fly over the surface of the storage disc in non-contacting fashion. This air cushion collapses given downward transgression of a minimum relative speed between magnetic head and storage disc, so that the head lands on the disc surface. Such a landing dare not occur in the data region of the magnetic discs. A landing region that corresponds to an idle position of the rotational positioner is therefore usually defined on the magnetic storage disc. It is assured that the rotational positioner can be swivelled out of the idle position into the data region only when the disc storage drive is running.
In known rotational positioners, a latch means that only releases the rotational positioner after the disc storage drive has been activated is therefore provided. The latch means frequently has an enable magnet that allows a rotational motion of the swivel part only in the excited condition. In order to enable the rotational motion of the rotational positioner, the enable magnet is excited during the entire operating time of the magnetic disc storage, so that its armature remains attracted. The enable magnet must therefore be designed for continuous operation; at the same time, it represents an additional electromagnetic noise source during the operation of the magnetic disc storage.
In order to avoid these disadvantages, U.S. Pat. No. 4,710,834 discloses a positioner means for a magnetic disc storage comprising a latch means that has a latch magnetic instead of an enable magnet. The latch magnet is fashioned such in combination with a retaining spring that, following brief excitation, it mechanically holds itself and then releases the swivel part. The mechanical locking of the magnetic armature releases only when the swivel part itself swivels back into the idle position, so that the released magnetic armature blocks the swivel part. The dimensioning of the latch magnet is less critical in this solution since it is only briefly excited for the release of the swivel part. In the normal operating condition of the magnetic disc storage, moreover, the latch magnet carries no current and therefore does not form an electromagnetic noise source for the operation of the magnetic disc storage.
What the described latch mechanisms for rotational positioners nonetheless have in common is that, namely, a magnetic element that is at least briefly excited is provided in order to preve

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"51/4-in. Unit Holds 26 Megabytes", Electronics, Apr. 21, 1982, pp. 181, 182, 184.
"Design of a High Performance Rotary Positioner for a Magnetic Disk Memory", IEEE Transactions on Magnetics, vol. Mag. 17, No. 4, Jul. 1981, Winfrey et al.
"Motor in Spindle Gives Micro-Winchester Room for 140M Bytes", Mini-Micro Systems, Feb. 1983, pp. 143-148, Jack Swartz.

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