Browse Prior Art Database

Magnetic Member having Double Recording Surfaces

IP.com Disclosure Number: IPCOM000095618D
Original Publication Date: 1964-Mar-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 31K

Publishing Venue

IBM

Related People

Morrison, JR: AUTHOR [+3]

Abstract

The magnetic member utilizes a substrate 10 as a non-magnetic support for double recording magnetic layers 11 and 12 located on one side of substrate 10. Substrate 10 can be either a plastic material such as a MYLAR* web or it can be a non-magnetic metallic plate or disk such as aluminum or copper. The recording surfaces can be either plated or can be magnetic oxide particles in binder. They can be oriented or not with an easy axis of magnetization.

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Magnetic Member having Double Recording Surfaces

The magnetic member utilizes a substrate 10 as a non-magnetic support for double recording magnetic layers 11 and 12 located on one side of substrate 10. Substrate 10 can be either a plastic material such as a MYLAR* web or it can be a non-magnetic metallic plate or disk such as aluminum or copper. The recording surfaces can be either plated or can be magnetic oxide particles in binder. They can be oriented or not with an easy axis of magnetization.

Layer 11 is supported directly on substrate 10 and has a higher coercivity than outer layer 12. A larger current is used in a write head, not shown, to record on layer 11. This is because of its higher coercivity and greater distance from the head than layer 12. Information is then written with a lower write current on the lower coercivity layer 12. Because of the difference in coercivity, the lower write current for layer 12 does not switch the magnetic state of layer 11 and, hence, does not disturb its recorded information. Thus, layer 12 can be rerecorded without disturbing information on layer 11. Writing information on layer 11 also writes the same information on layer 12. *Trademark of E.I. du Pont de Nemours & Co.

Furthermore, to assist readout without interference between layers, the information is written at different angles on the two layers, preferably at 90 degrees with respect to each other. Thus, the information bits 13 on layer 11 can be written in longitudinal tracks. The information bits...