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

Bias Adjustment in Self Biasing Magnetic Head

IP.com Disclosure Number: IPCOM000093097D
Original Publication Date: 1967-May-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 2 page(s) / 23K

Publishing Venue

IBM

Related People

Bacon, JL: AUTHOR

Abstract

The magnetic head has a bias adjusting circuit. Head 1 has three legs A, B, and C with A and B forming an erase gap 2 and B and C forming a record-playback gap 3. High-frequency current through erase winding 4 generates erase flux in loop A-B and bias flux in loop B-C.

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 100% of the total text.

Page 1 of 2

Bias Adjustment in Self Biasing Magnetic Head

The magnetic head has a bias adjusting circuit. Head 1 has three legs A, B, and C with A and B forming an erase gap 2 and B and C forming a record- playback gap 3. High-frequency current through erase winding 4 generates erase flux in loop A-B and bias flux in loop B-C.

The amount of flux in leg B equals RC. omega/(RB+C) and in leg C equals RB. Omega(RB+RC). RB and RC are the reluctance of legs B and C respectively. The relative cross-sectional areas of legs A, B, and C can be arranged so that more flux than is necessary to establish bias flux normally exists in leg A.

The bias flux in leg C is adjusted to optimum value by increasing the reluctance of leg C. This is done with record winding 5 and capacitor 6 by varying the high-frequency impedance seen by winding 5. Increasing the value of capacitor 6 tends to short-circuit coil 5, the reluctance of leg C increases, and the bias flux decreases. With a high enough erase-bias frequency, the reactance of capacitor 6 is large enough at audio frequencies so that recording current is not shunted. With a combination record-playback head, the playback turns can be used as a reluctance adjusting coil. Capacitor 6 can be left on the head in playback to resonate with head inductance at high audio playback frequencies.

1

Page 2 of 2

2

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