Bulk tape eraser with rotating magnetic field
US4423460A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 4, 1982 |
| Grant date | Dec 27, 1983 |
| Priority date | — |
| Expiry date | Jan 4, 2002 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B5/0245
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
Apparatus is disclosed for bulk erasing magnetic tapes spirally wound on a carrier. A pair of magnetic structures are spaced apart by an air gap of sufficient width to receive the tape carrier. Circuitry is provided for producing a rotating magnetic field in the air gap substantially parallel with the tape. Preferably, the magnetic structures take the form of multi-legged iron cores. The cores are mounted so that corresponding legs on opposing cores have the same magnetic polarity. A phase shifter circuit is adapted to supply currents 90.degree. out of phase with one another to selected pairs of legs in the cores to create a rotating magnetic field in the air gap.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.