Magnetic recording medium

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Turning to FIG.
1 there is depicted a molded sheet 1, comprising layer 3 and bonded to one surface thereof a ferromagnetic plate 2.
The layer 3 comprises an organic binder, such as for example, synthetic rubber, chloroprene, chlorinated polyethylene, poly vinyl chloride, etc.
Uniformly dispersed throughout the binder are a plurality of domain sized particles of at least one of barium ferrite, strontium ferrite and lead ferrite.
The amount of ferrite to binder can be varied.
A suitable ratio can be 5 to 65% by volume particles and 95 to 35% by volume binder.
The barium ferrite, strontium ferrite and lead ferrite used herein can be prepared by using any known technique.
A favorable method is described in Ser.
No.
556,017 assigned to the Assignee hereof.
The ferrite may be characterized as being a hard magnetic material.
The sheet has high coercive force and high residual magnetic flux.
The plate 2 is made of a soft magnetic material, such as iron.
Thus, once magnetized, the ferrite particles will tend to remain magnetized until demagnetized or its direction of magnetization changed.
The plate 2, does not tend to hold its magnetization.
Instead it is used herein to facilitate the magnetization in a perpendicular direction of the ferrite particles.
It is important that the particles have a strong priority direction of magnetization, which is substantially perpendicular to the surfaces of the sheet.
With such orientation, and the permanent magnetic property of the particles, and the presence of plate 2 to facilitate magnetization of the particles in the perpendicular direction, the recording, reading and erasure of information by change of magnetic states cannot be accomplished by a magnetic head having the ordinary air gap.
The recording, reading and erasure may be done by an electromagnetic means discussed hereinbelow in greater detail.
Turning now to FIGS.
2A, 2B, 2C, 2D, 2E and 2F, there is depicted molded sheet 1, a magnetizing means 4 comprising energizing coil 5 connectable to a source of electrical energy not shown, and a soft magnetic core 6