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Generating Bias Field for Magneto-Optic Recording Using Permanent Magnets and Mechanical Actuator

IP.com Disclosure Number: IPCOM000038502D
Original Publication Date: 1987-Jan-01
Included in the Prior Art Database: 2005-Jan-31
Document File: 2 page(s) / 46K

Publishing Venue

IBM

Related People

Rugar, D: AUTHOR [+2]

Abstract

We have found a method which uses actuator-driven permanent magnets to generate a bias field. The method has the advantage of requiring very little power. Another advantage is that magnetic fields as high as 2 kilogauss can easily be obtained. Practical mechanical actuators allow switching times between 1 and 10 milliseconds, comparable to switching times of electromagnets. Fig. 1 shows the basic idea. Two rare earth magnets are joined in a junction with opposing polarities. An actuator translates the magnets in a direction perpendicular to the tracking direction of the head. The purpose of the actuator is to position one of the magnets over the focused laser beam during erasing, and to position the other (Image Omitted) magnet over the beam during writing. This is shown in Fig. 2.

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Generating Bias Field for Magneto-Optic Recording Using Permanent Magnets and Mechanical Actuator

We have found a method which uses actuator-driven permanent magnets to generate a bias field. The method has the advantage of requiring very little power. Another advantage is that magnetic fields as high as 2 kilogauss can easily be obtained. Practical mechanical actuators allow switching times between 1 and 10 milliseconds, comparable to switching times of electromagnets. Fig. 1 shows the basic idea. Two rare earth magnets are joined in a junction with opposing polarities. An actuator translates the magnets in a direction perpendicular to the tracking direction of the head. The purpose of the actuator is to position one of the magnets over the focused laser beam during erasing, and to position the other

(Image Omitted)

magnet over the beam during writing. This is shown in Fig. 2. By translating the magnets, the direction of the perpendicular component of the magnetic field can be chosen to be either up or down, allowing domains of either sign to be thermomagnetically written. The length of the junction magnet could be long enough to cover the entire data band on the disk. Thus, the magnet structure does not need to be moved in the radial direction when the optical head/lens moves from track to track. The mechanically actuated junction magnet provides a means to generate high magentic field strengths with a minimum of power consumption. It is useful for applications...