| 摘要 |
<p>Magnetic medium having a permanent magnetic feature to prevent erasure and counterfeiting. The magnetic medium, in one form, includes a body having a two-dimensional grid pattern of magnetically acicular particles forming a permanent magnetic feature. The magnetic medium, in another form, includes a body having a permanent pattern of magnetically isotropic particles having a coercivity greater than 200 Oe, such pattern formed by varying concentrations of magnetically isotropic particles.</p> |
