Combined wide-erase and read-write magnetic head

Claim 2

A combined erase and read-write magnetic head, comprising: an elongated magnetic recording surface having a longitudinal dimension and a substantially constant width transverse to said longitudinal dimension; an erase magnetic circuit having an erase gap in said recording surface, the length of said gap being along said longitudinal dimension of said surface and the width of said gap being transverse to said longitudinal dimension across the entire width of said surface, said erase gap being sufficiently long compared to said width of said erase gap to permit the generation of effective erasing magnetic fields beyond the ends of said width of said erase gap; a read-write magnetic circuit having a read-write gap in said recording surface spaced from said erase gap, the length of said read-write gap being in the direction of said longitudinal dimension and the width of said read-write gap being transverse to said longitudinal dimension across the entire width of said surface and substantially the same width as said erase gap, said erase magnetic circuit and said read-write magnetic circuit having a common magnetic path between said erase gap and said read-write gap.

Claim 3

The combined erase and read-write magnetic head defined in claim 1 including: an erase pole piece in said erase magnetic circuit; a read-write pole piece in said read-write magnetic circuit; a common pole piece in both said erase and said read-write magnetic circuits; and a cross piece for closing said erase and saId read-write magnetic circuits, said cross piece being mounted across said erase pole piece, said read-write pole piece and said common piece at ends thereof opposite said erase and said read-write gaps.

Claim 4

The combined erase and read-write magnetic head defined in claim 2 including: an erase coil mountable on said erase pole piece; a read-write coil mountable on said read-write pole piece; said erase coil and said read-write coil being mounted on said erase pole piece and said read-write pole piece prior to mounting said cross piece across said pole pieces.

Claim 5

The combined erase and read-write magnetic head defined in claim 2 wherein: said common pole piece is of increased cross-sectional area compared to said erase and said read-write pole pieces.

Claim 6

A combined erase and read-write magnetic head, comprising: an elongated magnetic recording surface having a longitudinal dimension and a substantially constant width transverse to said longitudinal dimension; an erase magnetic circuit having an erase gap in said recording surface, the length of said gap being along said longitudinal dimension of said surface and the width of said gap being transverse to said longitudinal dimension across the entire width of said surface, said erase gap being sufficiently long compared to said width of said erase gap to permit the generation of effective erasing magnetic fields beyond the ends of said width of said erase gap; a read-write magnetic circuit having a read-write gap in said recording surface spaced from said erase gap, the length of said read-write gap being in the direction of said longitudinal dimension and the width of said read-write gap being transverse to said longitudinal dimension across the entire width of said surface and substantially the same width as said erase gap, said erase magnetic circuit and said read-write magnetic circuit having a common magnetic path between said erase gap and said read-write gap; an erase pole piece in said erase magnetic circuit; a read-write pole piece in said read-write magnetic circuit; a common pole piece in both said erase and said read-write magnetic circuits; an auxiliary common pole piece member mounted on said common pole piece to increase the cross-sectional area thereof; and a cross piece for closing said erase and said read-write magnetic circuits, said cross piece being mounted across said erase pole piece, said read-write pole piece and said common piece at ends thereof opposite said erase and said read-write gaps.

Claim 7

A combined erase and read-write magnetic head, comprising: an elongated magnetic recording surface having a longitudinal dimension and a substantially constant width transverse to said longitudinal dimension; an erase magnetic circuit having an erase gap in said recording surface, the length of said gap being along said longitudinal dimension of said surface and the width of said gap being transverse to said longitudinal dimension across the entire width of said surface, said erase gap being sufficiently long compared to said width of said erase gap to permit the generation of effective erasing magnetic fields beyond the ends of said width of said erase gap; a read-write magnetic circuit having a read-write gap in said recording surface spaced from said erase gap, the length of said read-write gap being in the direction of said longitudinal dimension and the width of said read-write gap being transverse to said longitudinal dimension across the entire width of said surface and substantially the same width as said erase gap, said erase magnetic circuit and said read-write magnetic circuit having a common magnetic path between said erase gap and said read-write gap; an erase pole piece in said erase magnetic circuit; a read-write pole piece in said read-write magnetic circuit; a common pole piece in both said erase and said read-write magnetic circuits; an auxiliary common pole piece member mounted on said common pole piece to increase the cross-sectional area thereof; and a cross piece for closing said erase and said read-write magnetic circuits, said cross piece being mounted across said erase pole piece, said read-write pole piece and said common piece at ends thereof opposite said erase and said read-write gaps.

Claim 8

A combined erase and read-write magnetic head, comprising: an elongated magnetic recording surface having a longitudinal dimension and a substantially constant width transverse to said longitudinal dimension; an erase magnetic circuit having an erase gap in said recording surface, the length of said gap being along said longitudinal dimension of said surface and the width of said gap being transverse to said longitudinal dimension across the entire width of said surface, said erase gap being sufficiently long compared to said width of said erase gap to permit the generation of effective erasing magnetic fields beyond the ends of said width of said erase gap; a read-write magnetic circuit having a read-write gap in said recording surface spaced from said erase gap, the length of said read-write gap being in the direction of said longitudinal dimension and the width of said read-write gap being transverse to said longitudinal dimension across the entire width of said surface and substantially the same width as said erase gap, said erase magnetic circuit and said read-write magnetic circuit having a common magnetic path between said erase gap and said read-write gap; an erase pole piece in said erase magnetic circuit; a read-write pole piece in said read-write magnetic circuit; a common pole piece in both said erase and read-write magnetic circuits; an auxiliary magnetic piece attached to said erase pole piecE and said common pole piece, said auxiliary piece both closing said erase magnetic circuit and increasing the cross-sectional area of said common pole piece; and a cross piece for closing said read-write magnetic circuit, said cross piece being mounted between said read-write pole piece and said common piece.

Claim 9

A combined erase and read-write magnetic head, comprising: an elongated magnetic recording surface having a longitudinal dimension and a substantially constant width transverse to said longitudinal dimension; an erase magnetic circuit having an erase gap in said recording surface, the length of said gap being along said longitudinal dimension of said surface and the width of said gap being transverse to said longitudinal dimension across the entire width of said surface, said erase gap being sufficiently long compared to said width of said erase gap to permit the generation of effective erasing magnetic fields beyond the ends of said width of said erase gap; a read-write magnetic circuit having a read-write gap in said recording surface spaced from said erase gap, the length of said read-write gap being in the direction of said longitudinal dimension and the width of said read-write gap being transverse to said longitudinal dimension across the entire width of said surface and substantially the same width as said erase gap, said erase magnetic circuit and said read-write magnetic circuit having a common magnetic path between said erase gap and said read-write gap; an erase pole piece in said erase magnetic circuit; a read-write pole piece in said read-write magnetic circuit; a common pole piece in both said erase and read-write magnetic circuits; an auxiliary magnetic piece attached to said erase pole piecE and said common pole piece, said auxiliary piece both closing said erase magnetic circuit and increasing the cross-sectional area of said common pole piece; and a cross piece for closing said read-write magnetic circuit, said cross piece being mounted between said read-write pole piece and said common piece.

Claim 10

The combined erase and read-write magnetic head defined in claim 6, including: an erase coil mounted on said erase pole piece; a read-write coil mounted on said read-write pole piece, said erase coil and said read-write coil being mounted on said erase pole piece and said read-write pole piece prior to mounting said auxiliary erase magnetic piece and said cross piece.

Claim 11

A combined erase and read-write magnetic head, comprising: an elongated magnetic recording surface having a longitudinal dimension and a substantially constant width transverse to said longitudinal dimension; an erase magnetic circuit having an erase gap in said recording surface, the length of said gap being along said longitudinal dimension of said surface and the width of said gap being transverse to said longitudinal dimension across the entire width of said surface, said erase gap being sufficiently long compared to said width of said gap to permit the generation of effective erasing magnetic fields beyond the ends of said width of said erase gap; a read-write magnetic circuit having a read-write gap in said recording surface spaced from said erase gap, the length of said read-write gap being along said longitudinal dimension and the width of said read-write gap being transverse to said longitudinal dimension across the entire width of said surface and substantially the same width as said erase gap; an erase pole piece; a read-write pole piece; a common pole piece, said erase pole piece, said read-write pole piece and said common pole piece having elongated members spaced and substantially parallel to each other with said erase gap being formed between ends of said erase pole piece and said common pole piece and said read-write gap being formed between said read-write pole piece and said common pole piece; an erase coil mounted around said erase pole piece; a read-write coil mounted around said read-write pole piece; an auxiliary magnetic piece having an elongated member mounted along said common pole piece and across member mounted across the open ends of said erase pole piece and said common pole piece to increase the magnetic cross-sectional area of said common pole piece and close said erase magnetic circuit; a cross piece mounted across the open ends of said read-write pole piece and said common pole piece to close said read-write magnetic circuit.

Claim 12

A combined erase and read-write magnetic head, comprising: an elongated magnetic recording surface having a longitudinal dimension and a substantially constant width transverse to said longitudinal dimension; an erase magnetic circuit having an erase gap in said recording surface, the length of said gap being along said longitudinal dimension of said surface and the width of said gap being transverse to said longitudinal dimension across the entire width of said surface, said erase gap being sufficiently long compared to said width of said gap to permit the generation of effective erasing magnetic fields beyond the ends of said width of said erase gap; a read-write magnetic circuit having a read-write gap in said recording surface spaced from said erase gap, the length of said read-write gap being along said longitudinal dimension and the width of said read-write gap being transverse to said longitudinal dimension across the entire width of said surface and substantially the same width as said erase gap; an erase pole piece; a read-write pole piece; a common pole piece, said erase pole piece, said read-write pole piece and said common pole piece having elongated members spaced and substantially parallel to each other with said erase gap being formed between ends of said erase pole piece and said common pole piece and said read-write gap being formed between said read-write pole piece and said common pole piece; an erase coil mounted around said erase pole piece; a read-write coil mounted around said read-write pole piece; an auxiliary magnetic piece having an elongated member mounted along said common pole piece and across member mounted across the open ends of said erase pole piece and said common pole piece to increase the magnetic cross-sectional area of said common pole piece and close said erase magnetic circuit; a cross piece mounted across the open ends of said read-write pole piece and said common pole piece to close said read-write magnetic circuit.

Claim 13

The combined erase and read-write magnetic head defined in claim 8, wherein: said length of said erase gap is approximately one-half of the width of said elongated surface.