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Fast Rise Time Bias Coil Driver

IP.com Disclosure Number: IPCOM000037848D
Original Publication Date: 1989-Jul-01
Included in the Prior Art Database: 2005-Jan-30
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Bui, N: AUTHOR [+3]

Abstract

The bias coil is used in magneto-optic recording to create a magnetic field in the active layers during erase and writing. To help lower the steady state heat dissipation, it is desirable to use coils with large number of turns and high inductance. This disclosure deals with driver designs that can overcome the inductance to establish a steady-state field in a shorter time.

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Fast Rise Time Bias Coil Driver

The bias coil is used in magneto-optic recording to create a magnetic field in the active layers during erase and writing. To help lower the steady state heat dissipation, it is desirable to use coils with large number of turns and high inductance. This disclosure deals with driver designs that can overcome the inductance to establish a steady-state field in a shorter time.

The idea is to double the drive voltage to the coil during the transient period. Initially, both +12 volts and -12 volts are applied to the two terminals of the coil. Once the current in the coil is established, one end of the coil is switched to ground level. The reduction in drive voltage helps to lower heat dissipation.

In a second design, a capacitor is charged to -12 volts to provide the initial high drive voltage. Thus, the driver circuits can operate with +12 volts alone.

A third design achieves the fast rise time by changing the inductance of the coil. The windings on the coil are divided into two independent halves. Initially, the two halves are connected in parallel for fast rise time. After the currents in the coils are established, the two halves are reconnected in series.

Disclosed anonymously.

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