Bulk tape eraser with rotating magnetic field
AssigneeLDJ Electronics, Inc.
InventorsLeon D. Jackson, Dan O. Morris
Life of this patent
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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.
Claims9
Apparatus for bulk erasing magnetic tapes spirally wound about an axis on a tape carrier, said apparatus comprising:
- first and second magnetic structures, each having a set of pole faces, each said set being arranged so that the pole faces of each structure oppose each other and are spaced by an air gap of sufficient width to receive the tape carrier therein;
- and
- circuit means coupled to the first and second structures for electrically producing a rotating magnetic field in the air gap substantially transverse to the tape carrier axis for erasing the tape by maintaining opposing pole faces in each structure with the same magnetic polarities.
Apparatus for bulk erasing magnetic tape spirally wound about at least one axis of a tape carrier, said apparatus comprising:
- a first structure having a first set of at least four magnetic poles depending therefrom parallel to a given axis, each pole including current carrying windings thereon wound so that opposing pairs of the poles in the first structure have opposite magnetic polarities;
- a second structure having a second set of magnetic poles corresponding in number to the first set of poles, said second set of poles including current carrying windings thereon wound so that opposing poles in the second structure have opposite magnetic polarity, the second set of poles being spaced in opposed relationship with poles of the same magnetic polarity in the first structure by an air gap of sufficient width to receive the tape carrier therein;
- and
- circuit means coupled to the current carrying windings of the poles of the first and second structures for electrically producing a rotating magnetic field in a plane transverse to said given axis for erasing the tape in the tape carrier, said circuit means being operative to supply atlernating currents of different phases to adjacent poles in each set while maintaining opposing poles across the air gap with the same magnetic polarities.
Dependencies are inferred from the claim text.