Dismiss
InnovationQ will be updated on Sunday, Oct. 22, from 10am ET - noon. You may experience brief service interruptions during that time.
Browse Prior Art Database

MULTIPLEXING THECHNIGUE FOR THERMOREMANENT MAGNETIZATION

IP.com Disclosure Number: IPCOM000025206D
Original Publication Date: 1984-Feb-29
Included in the Prior Art Database: 2004-Apr-04
Document File: 4 page(s) / 187K

Publishing Venue

Xerox Disclosure Journal

Abstract

It is known that magnetic recording may be accomplished by using thermoremanent magnetization induced by local resistive heating in a layered magnetic recording medium. The passage of current between any two styli of an array of styli in contact with the recording medium will locally heat a small area thereof. A tiny magnetic spot is formed when recording medium material is heated resistively past the Curie temperature and allowed to cool in the presence of an applied external magnetic field. Heating without a field does not produce magnetization and will erase a previously magnetized area.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 52% of the total text.

Page 1 of 4

XEROX DISCLOSURE JOURNAL

~ MULTIPLEXING TECHNIOUE FOR ProDosed Classification

.

THERMOREMANENT MAGNETIZATION Frank C. Genovese
James W. Lannom

US: C1. 346/154 Int. Cl. Gold 15/06

FIRST GROUP OF 64 NIBS SECCFJD GROUP OF 64 NIBS

f

h

\7

Volume 9 Number 1 January/February 1984 19

[This page contains 1 picture or other non-text object]

Page 2 of 4

MULTIPLEXING TECHNIQUE FOR THERMOREMANENT MAGNETIZATION

ir ContW

flG 3

It is known that magnetic recording may be accomplished by using thermoremanent magnetization induced by local resistive heating in a layered magnetic recording medium. The passage of current between any two styli of an array of styli in contact with the recording medium will locally heat a small area thereof. A tiny magnetic spot is formed when recording medium material is heated resistively past the Curie temperature and allowed to cool in the presence of an applied external magnetic field. Heating without a field does not produce magnetization and will erase a previously magnetized area.

20

    XEROX DISCLOSURE JOURNAL Volume 9 Number 1 January/February 1984

[This page contains 1 picture or other non-text object]

Page 3 of 4

M UL TIP L E X I N G TECH N IQ U E FOR THE R A4 0 RE MANE NT h4 A G N ETIZ AT I0 N (Cont'd)

In principal, to form an image, current carrying contacts or nibs are selectively energized. However, in order to satisfy the resolution requirements of irna.ge quality, the total number of individual contacts in the array must be so large 1200- 800/in) that individual control of each contact is either impractical or requires special technologies, such as thin film transistor networks.

An alternative approach is to use a multiplexing arrangement. Such a multiplexing scheme utilizes a segmented applied magnetic field so that both heat generated by the localized current, and magnetic field must be simultaneously applied to induce magnetism. As shown in Figures 1 and 2, current carrying nibs 10, numbered N1, N2, etc., are connected in 128 groups of 32 to form a linear array of 4096 nibs, and a magnet 12 segmented into 64 separate segments 13 (numbered 131, 132, 133, etc.) each individually controlled by associated coils 18 (numbered 181, 182, 183, etc.). The segments are operated in pairs to avoid uncertainties in the area between segments. The construction of the magnet 12 resembles that of an oversized multigap recording head commonly used in digital tape recorders and has a magnetizing gap 14. The recording medium 16 is omitted from Figure 1 and the magnetic segment is schematically represented in Figure 2 for clarity.

Figure 1 is an elevation view across the width of the recording medium 16 (not shown) having the nibs 10 and magnet segments 13 located transverse to the direction of movement of the recording medium 16 (Le., moving into or out of page) as shown by arrow 20 in Figure 2, where Figure 2 is a side view of Figure 1.

Data in the form of a field pattern is first impressed on both the even numbered coils...