Dispersion and Orientation Magnet for the Manufacture of Magnetic Disks
Original Publication Date: 1986-Feb-01
Included in the Prior Art Database: 2005-Mar-08
An electromagnet with a toroidal yoke is described, which, depending upon the polarity of the magnetic field and the excitation current, respectively, acts both as a dispersion and an orientation magnet for the magnetic particles during the manufacture of particulate magnetic record carriers, in particular magnetic disks. The new type of magnet eliminates coating errors. In the dispersion/spin-off phase, the proposed magnet generates a purely vertical magnetic field retaining the particle dispersion and preventing so-called "windows". Such a magnetic field straightens the particles. The small coating thickness prevents the formation of particle chains, parallel particles being spaced from each other, thus retaining the particle dispersion.