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Magnetic Autolock

IP.com Disclosure Number: IPCOM000034802D
Original Publication Date: 1989-Apr-01
Included in the Prior Art Database: 2005-Jan-27
Document File: 2 page(s) / 49K

Publishing Venue

IBM

Related People

Brue, BM: AUTHOR [+3]

Abstract

An autolock design is described which avoids common failures by employing a magnet instead of the conventional mechanical and electrical apparatus. In Fig. 1a, a mounting bracket 1 with a permanent magnet and two poles 2 is fixed to the frame of the file. Another iron pole called the bobbin pole 3 is mounted inside of the moving coil of the voice coil motor on the actuator. These poles are positioned in such a way that when the actuator is in the lock position or landing zone 4 (see Fig. 1b), the pole tips are in alignment. The magnetic attraction will tend to hold the actuator in this position. When the file is powered on, the actuator is moved away from the lock position by a current applied to the voice coil. The current causes a magnetic flux in the bobbin pole.

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Magnetic Autolock

An autolock design is described which avoids common failures by employing a magnet instead of the conventional mechanical and electrical apparatus. In Fig. 1a, a mounting bracket 1 with a permanent magnet and two poles 2 is fixed to the frame of the file. Another iron pole called the bobbin pole 3 is mounted inside of the moving coil of the voice coil motor on the actuator. These poles are positioned in such a way that when the actuator is in the lock position or landing zone 4 (see Fig. 1b), the pole tips are in alignment. The magnetic attraction will tend to hold the actuator in this position. When the file is powered on, the actuator is moved away from the lock position by a current applied to the voice coil. The current causes a magnetic flux in the bobbin pole. The magnetic polarities are such that this flux tends to buck or cancel the flux from the permanent magnet. The result is that the attractive force is fully or partially cancelled and the actuator is free to move. After the actuator has moved out of the landing zone, the autolock poles are far enough apart so that there is negligible force even with no current or current in the opposite direction in the voice coil. To latch up, a retract current is applied to the voice coil to drive it toward the lock position. The current direction for retract is such that the flux in the bobbin will reinforce the flux for the permanent magnet and will tend to draw to and hold it in that position. I...