US4450494A
Expired / Lapsed
US
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Magnetic head
Assignee: Hitachi Ltd
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Filing: 1981-09-22
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Granted: 1984-05-22
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Expires: 2001-09-22
Abstract
Abstract A magnetic head having a magnetic core formed by facing a pair of magnetic substances through a working gap at a head section confronting a magnetic recording medium is disclosed in which at least one of the magnetic substances has magnetic anisotropy, and an angle alpha (in a C-shaped core half) and/or an angle alpha ' (in an I-shaped core half) between a core surface confronting the magnetic recording medium and a direction having a maximum magnetic permeability in a main magnetic circuit plane of the magnetic substance having magnetic anisotropy is made larger than an orientation angle of the above direction for making minimum the magnetic reluctance of the main magnetic circuit of the magnetic core by beta (for alpha ) and/or beta ' (for alpha ') to improve the recording/reproducing characteristic of the magnetic head, where beta is given by a formula <IMAGE> is equal to or less than 25 DEG , D indicates a depth of the working gap, L* indicates an effective length of an oblique part for forming the working gap, and min [a, b] indicates the smaller of a and b.
Inventors
- 👤 Hideo Fujiwara
- 👤 Mitsuhiro Kudo
- 👤 Teizo Tamura
- 👤 Nobuyuki Sugishita
- 👤 Yoshihiro Shiroishi
- 👤 Takeshi Kimura
- 👤 Kiminari Shinagawa
- 👤 Noriyuki Kumasaka
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 16:55
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/127; G11B5/133; G11B5/187; G11B5/193
Claims Analysis
Total Claims: 30
Claim 1
Independent Claim
180 words
A magnetic head having a magnetic core formed by facing a pair of magnetic substances through a working gap at a head section confronting a magnetic recording medium, comprising an oblique part made by at least one of said magnetic substances in the neighborhood of said working gap for forming said working gap, an inner wall of said oblique part being inclined at an angle with a face confronting said magnetic recording medium, said oblique part being made of a magnetic material having magnetic anisotropy, an angle α between a direction having a maximum magnetic permeability in a main magnetic circuit plane of said oblique part and said face confronting said magnetic recording medium being larger than an orientation angle of said direction for making minimum a magnetic reluctance of a main magnetic circuit of said magnetic core by an angle β, said angle β being given by the following formula: ##EQU12## wherein D indicates a depth of said working gap, L*, indicates an effective length of said oblique part, and min ##EQU13## indicates the smaller of ##EQU14## and 50°.
Claim 2
Dependent Claim
180 words
A magnetic head having a magnetic core formed by facing a pair of magnetic substances through a working gap at a head section confronting a magnetic recording medium, comprising an oblique part made by at least one of said magnetic substances in the neighborhood of said working gap for forming said working gap, an inner wall of said oblique part being inclined at an angle with a face confronting said magnetic recording medium, said oblique part being made of a magnetic material having magnetic anisotropy, an angle α between a direction having a maximum magnetic permeability in a main magnetic circuit plane of said oblique part and said face confronting said magnetic recording medium being larger than an orientation angle of said direction for making minimum a magnetic reluctance of a main magnetic circuit of said magnetic core by an angle β, said angle β being given by the following formula: ##EQU12## wherein D indicates a depth of said working gap, L*, indicates an effective length of said oblique part, and min ##EQU13## indicates the smaller of ##EQU14## and 50°.
Claim 3
Dependent Claim
18 words
A magnetic head according to claim 1, wherein said angle β is given by the following formula: ##EQU15##
Claim 4
Dependent Claim
18 words
A magnetic head according to claim 1, wherein said angle β is given by the following formula: ##EQU16##
Claim 5
Dependent Claim
19 words
A magnetic head according to claim 1, wherein said angle α lies within a range from 10° to 45°.
Claim 6
Dependent Claim
18 words
A magnetic head according to claim 1, wherein said angle α is given by the following formula: ##EQU17##
Claim 7
Dependent Claim
18 words
A magnetic head according to claim 1, wherein said angle α is given by the following formula: ##EQU18##
Claim 8
Dependent Claim
18 words
A magnetic head according to claim 1, wherein said angle α is given by the following formula: ##EQU19##
Claim 9
Dependent Claim
47 words
A magnetic head according to claim 1, wherein an angle θ between said inner wall of said oblique part and said face confronting said magnetic recording medium lies substantially within a range from 20° to 35°, and said angle α is given by the following formula: ##EQU20##
Claim 10
Dependent Claim
18 words
A magnetic head according to claim 8, wherein said angle α is given by the following formula: ##EQU21##
Claim 11
Dependent Claim
18 words
A magnetic head according to claim 8, wherein said angle α is given by the following formula: ##EQU22##
Claim 12
Dependent Claim
47 words
A magnetic head according to claim 1, wherein an angle θ between said inner wall of said oblique part and said face confronting said magnetic recording medium lies substantially within a range from 35° to 60°, and said angle α is given by the following formula: ##EQU23##
Claim 13
Dependent Claim
18 words
A magnetic head according to claim 11, wherein said angle α is given by the following formula: ##EQU24##
Claim 14
Dependent Claim
18 words
A magnetic head according to claim 11, wherein said angle α is given by the following formula: ##EQU25##
Claim 15
Dependent Claim
180 words
A magnetic head having a magnetic core, comprising first and second magnetic substances facing each other through a working gap at a head section confronting a magnetic recording medium for forming said magnetic core, only said second magnetic substance having at a portion thereof near said working gap an oblique part for forming said working gap, an inner wall of said oblique part being inclined at an angle with a face confronting said magnetic recording medium, said first magnetic substance being a magnetic material having magnetic anisotropy, a side face of said first magnetic substance being opposite to said oblique part of said second magnetic substance through a nonmagnetic layer, an angle α' between a direction having a maximum magnetic permeability at a part of said first magnetic substance near said working gap in a main magnetic circuit plane of said magnetic core and said face confronting said magnetic recording medium being larger than an orientation angle of said direction for making minimum a magnetic reluctance of a main magnetic circuit of said magnetic core by about 25° or less.
Claim 16
Dependent Claim
180 words
A magnetic head having a magnetic core, comprising first and second magnetic substances facing each other through a working gap at a head section confronting a magnetic recording medium for forming said magnetic core, only said second magnetic substance having at a portion thereof near said working gap an oblique part for forming said working gap, an inner wall of said oblique part being inclined at an angle with a face confronting said magnetic recording medium, said first magnetic substance being a magnetic material having magnetic anisotropy, a side face of said first magnetic substance being opposite to said oblique part of said second magnetic substance through a nonmagnetic layer, an angle α' between a direction having a maximum magnetic permeability at a part of said first magnetic substance near said working gap in a main magnetic circuit plane of said magnetic core and said face confronting said magnetic recording medium being larger than an orientation angle of said direction for making minimum a magnetic reluctance of a main magnetic circuit of said magnetic core by about 25° or less.
Claim 17
Dependent Claim
161 words
A magnetic head according to claim 1, wherein only a second one of said magnetic substances has at a portion thereof near said working gap said oblique part for forming said working gap, said inner wall of said oblique part is inclined at an angle with said face confronting said magnetic recording medium, a first one of said magnetic substances is a magnetic material having magnetic anisotropy, a side face of said first magnetic substance is opposite to said oblique part of said second magnetic substance through a nonmagnetic layer, and an angle α' between a direction having a maximum magnetic permeability at a part of said first magnetic substance near said working gap in a main magnetic circuit plane of said magnetic core and said face confronting said magnetic recording medium is larger than an orientation angle of said direction for making minimum a magnetic reluctance of a main magnetic circuit of said magnetic core by about 25° or less.
Claim 18
Dependent Claim
20 words
A magnetic head according to claim 15, wherein said angle α' lies substantially within a range from 15° to 45°.
Claim 19
Dependent Claim
122 words
A magnetic head according to claim 16, wherein said part of said first magnetic substance near said working gap is made smaller in thickness than the remaining part of said first magnetic substance to form a track width defining part having a thickness substantially equal to a track width, a ratio of a depth D of said working gap to a length L' of said track width defining part is in a range from 0.05 to 0.25, and said angle α' between said direction having a maximum magnetic permeability at said track width defining part in said main magnetic circuit plane of said magnetic core and said face confronting said magnetic recording medium lies substantially within a range from 25° to 45°.
Claim 20
Dependent Claim
19 words
A magnetic head according to claim 16, wherein said angle α and said angle α' differ from each other.
Claim 21
Dependent Claim
23 words
A magnetic head according to any one of claims 1 through 18, wherein said magnetic material having magnetic anisotropy is monocrystalline Mn-Zn ferrite.
Claim 22
Dependent Claim
23 words
A magnetic head according to any one of claims 1 through 18, wherein said magnetic material having magnetic anisotropy is oriented polycrystalline ferrite.
Claim 23
Dependent Claim
27 words
A magnetic head according to any one of claims 1 through 18, wherein said magnetic material having magnetic anisotropy is a monocrystalline or oriented polycrystalline magnetic metal.
Claim 24
Dependent Claim
94 words
A magnetic head according to any one of claims 1 through 18, wherein at least one of a pair of track width defining parts is made of monocrystalline Mn--Zn ferrite having a positive magnetocrystalline anisotropy constant K 1 , a main magnetic circuit plane of said track width defining part is substantially formed of a crystal plane (110), and a residual stress in said track width defining part is restricted or controlled so that a direction <100> in said plane (110) is a direction having a maximum magnetic permeability in a low frequency range.
Claim 25
Dependent Claim
95 words
A magnetic head according to any one of claims 1 through 18, wherein at least one of a pair of track width defining parts is made of monocrystalline Mn--Zn ferrite having a positive magnetocrystalline anisotropy constant K 1 , and a main magnetic circuit plane of said track width defining part is substantially formed of a crystal plane (110), and a residual stress in said track width defining part is restricted or controlled so that a direction <110> in said plane (110) is a direction having a maximum magnetic permeability in a high frequency range.
Claim 26
Dependent Claim
94 words
A magnetic head according to any one of claims 1 through 18, wherein at least one of a pair of track width defining parts is made of monocrystalline Mn--Zn ferrite having a negative magnetostrictive constant λ 100 , and a main magnetic circuit plane of said track width defining part is substantially formed of a crystal plane (110), and a residual stress in said track width defining part is restricted or controlled so that a direction <100> in said plane (110) is a direction having a maximum magnetic permeability in a low frequency range.
Claim 27
Dependent Claim
110 words
A magnetic head according to any one of claims 1 through 18, wherein at least one of a pair of track width defining parts is made of monocrystalline Mn--Zn ferrite having a negative magnetostrictive constant λ 100 and a positive magnetostrictive constant λ 111 , a main magnetic circuit plane of said track width defining part is substantially formed of a crystal plane (110), and a tension is made to remain in a side surface of said track width defining part parallel to said main magnetic circuit plane so that a direction <100> in said plane (110) is a direction having a maximum magnetic permeability in a high frequency range.
Claim 28
Dependent Claim
110 words
A magnetic head according to any one of claims 1 through 18, wherein at least one of a pair of track width defining parts is made of monocrystalline Mn--Zn ferrite having a negative magnetostrictive constant λ 100 and a positive magnetostrictive constant λ 111 , a main magnetic circuit plane of said track width defining part is substantially formed of a crystal plane (110), and a tension is made to remain in a side surface of said track width defining part parallel to said main magnetic circuit plane so that a direction <110> in said plane (110) is a direction having a maximum magnetic permeability in a low frequency range.
Claim 29
Dependent Claim
94 words
A magnetic head according to any one of claims 1 through 18, wherein at least one of a pair of track width defining parts is made of monocrystalline Mn--Zn ferrite having a negative magnetocrystalline anisotropy constant K 1 , a main magnetic circuit plane of said track width defining part is substantially formed of a plane including one crystallographic axis <111>, and a residual stress in said track width defining part is restricted so that the direction of said axis <111> is a direction having a maximum magnetic permeability in a low frequency range.
Claim 30
Dependent Claim
105 words
A magnetic head according to any one of claims 1 through 18, wherein at least one of a pair of track width defining parts is made of monocrystalline Mn--Zn ferrite having a negative magnetocrystalline anisotropy constant K 1 , a main magnetic circuit plane of said track width defining part is substantially formed of a plane including one crystallographic axis <111>, and a residual stress in said track width defining part is restricted so that a direction having a maximum magnetic permeability in a plane parallel to said main magnetic circuit plane in a high frequency range is a direction perpendicular to said axis <111>.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-05-22 | 1987-11-21 | 1988-05-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-05-22 | 1991-11-21 | 1992-05-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-05-22 | 1995-11-21 | 1996-05-22 | $7700.00 | Window Closed / Lapsed |