Magnetic structure for suppressing magnetic cross talk among rotary transducers on a common rotary disc

US4816950A · kind A · utility

Assignee

• Robert Bosch GmbH · DE

Inventors

• Richard Heinz · Munich, DE
• Willi Hartmann · Lemberg, DE
• Hartmut Willmann · Camburg, DE
• Josef Walter · Würzburg, DE

Key dates

• Filing date: Jul 1, 1987
• Grant date: Mar 28, 1989
• Expiry date: Jul 1, 2007

Classification

• Technology area (CPC G): Physics
• CPC primary: G11B5/11
• WIPO field: Audio-visual technology
• WIPO sector: Electrical engineering

Abstract

A strip of easily magnetizable material of low remanence, having magnetic properties equal to or better than those of the core of the magnetic heads on a revolving headwheel of a video tape machine is provided as a magnetic shunt for each head, disposed in the neighborhood of the core gap, but spaced therefrom at a distance much greater than the gap width, for reducing the spread of stray flux when the head is used for recording and intercepting stray flux from other heads when the head is in the playback mode. Among the many ways in which the shunt can be provided are individual bridge strip mounted on the headwheel to bridge over each head laterally, a horseshoe-shaped strip covering the annular gap in which the headwheel revolves for the portions of that gap over which the tape passes, but spaced away from the tape, and strips mounted on the stationary guide drums or embedded in the headwheel periphery. The reduction and interception of stray flux is of important advantage when a tape reading head is in operation at the same time as a recording head on the same headwheel.