Browse Prior Art Database

MATRIX ADDRESSING FOR THIN FILM MAGNETIC HEAD ARRAYS

IP.com Disclosure Number: IPCOM000025463D
Original Publication Date: 1985-Aug-31
Included in the Prior Art Database: 2004-Apr-04
Document File: 6 page(s) / 347K

Publishing Venue

Xerox Disclosure Journal

Abstract

Full width, head-per-track, thin film magnetic head arrays generally have considerable cost and recording speed advantages over rotary recording systems, when used for electronic image input to magnetographic printing systems. Since thin film heads require high currents (about an amp per head), it is desirable to minimize the number of wires and connectors, so that parallel addressing of the entire array (3000-6000 elements) is out of the question. Thus, some form of matrix addressing is required which minimizes both the electric current demands and the number of wires. Consideration of the latent image requirements, switching rates, recorded spot size, process speed, thermal considerations, and electric current limitations lead to some design constraints regarding matrix addressed head arrays for magnetic imaging; for example, shared lead designs may not be compatible with latent image requirements and, therefore, some parallel as well as sequential addressing will have to be employed to keep up with copier process speeds.

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Page 1 of 6

XEROX DISCLOSURE JOURNAL

MATRIX ADDRESSING FOR THIN FILM MAGNETIC HEAD ARRAYS Daniel F. Blossey

Proposed Classification
U.S. CI. 340/174 Int. CI. H04q

F/G. 2

I

1

F/G. 3

Volume 10 Number 4 July/August 1985 20 1

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

Page 2 of 6

MATRIX ADDRESSING FOR THIN FILM MAGNETIC HEAD ARRAYS (Cont'd)

SEQUENTIAL ADDRESSING SWITCH

NUMBER

PARALLEL ADDRESSING SWITCH

(3

- FOLD) NUMBER

ii

uuuuuuuuuuuuuuuuuuuuu

16 18 20 22 24 26 28 30 32 34 36

HEAD NUMBER

2

4 68 10 12

4 16 I8 20 22 24 26 28 30 32 34 36

HEAD NUMBER

FIG. 5

202

   XEROX DISCLOSURE JOURNAL Volume 10 Number 4 July/August 1985

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

Page 3 of 6

MATRIX ADDRESSING FOR THIN FILM MAGNETIC HEAD ARRAYS (Cont'd)

Full width, head-per-track, thin film magnetic head arrays generally have considerable cost and recording speed advantages over rotary recording systems, when used for electronic image input to magnetographic printing systems. Since thin film heads require high currents (about an amp per head), it is desirable to minimize the number of wires and connectors, so that parallel addressing of the entire array (3000-6000 elements) is out of the question. Thus, some form of matrix addressing is required which minimizes both the electric current demands and the number of wires. Consideration of the latent image requirements, switching rates, recorded spot size, process speed, thermal considerations, and electric current limitations lead to some design constraints regarding matrix addressed head arrays for magnetic imaging; for example, shared lead designs may not be compatible with latent image requirements and, therefore, some parallel as well as sequential addressing will have to be employed to keep up with copier process speeds.

As a matter of practicality, rapid raster recording of magnetic latent irnages can be accomplished one of two ways: (1) use a few heads and high head-to-media speeds of about 1000 ips as in video recording, or (2) use many heads (several thousand) and low head-to-media speeds of a few ips. Both approaches have their own particular advantages and disadvantages. High head-to-media speeds require rotary recording and complicated tape transport mechanisms, whereas the multi-head (head-per-track) approach puts the emphasis on head fabrication and addressability. If fabrication and addressability problems are overcome, the thin film head-per-track arrays have considerable cost and speed advantages over rotary recording structures.

If, for example, a rotary recorder has eight heads rotating at 5000 rprns inside a tape wrap which translates past the heads during the recording, a full page may be recorded at 750 lpi in 10 seconds. Anhysteretic (a.c. bias) recording techniques may be used in which the image signal is superimposed on a high level
a.c. bias so that when there is no signal the heads erase the media and when there is an image signal, the heads record the proper spacial...