US4751779A
Expired / Lapsed
US
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Method of producing a core for magnetic head
Assignee: DS SCANNER Co Ltd 22 IZUMI-CHO 2-CHOME HIGASHI-KU OSAKA CITY JAPAN
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Filing: 1987-03-30
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Granted: 1988-06-21
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Expires: 2007-03-30
Abstract
Abstract A core for magnetic head, which has a surface roughness of not higher than 2 μm in the side wall of a groove for defining the track width of the core, can be obtained by subjecting at least a portion, which defines the track width, of a gapped bar made of ferrite and having a coil turn hole and a magnetic gap, to a laser-induced etching under a condition that a laser light having a power of 50-1,100 mW and a focused beam diameter of not larger than 20 μm is irradiated to at least the track width-defining portion at a scanning speed of 2-110 μm/sec in a halogen gas- or halide gas-containing atmosphere kept to a gas pressure of 10-200 Torr.
Inventors
- 👤 Shohei Nagatomo
- 👤 Mikio Takai
- 👤 Hideto Sandaiji
- 👤 Soji Ohara
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 07:45
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/127; G11B5/187; G11B5/193; G11B5/133; G11B5/1335; Y; Y10; Y10T; Y10T29/00; Y10T29/49; Y10T29/49002; Y10T29/4902; Y10T29/49021; Y10T29/49032; Y10T29/49048; Y10T29/4905; Y10T29/49052
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
137 words
In a method of producing a core for magnetic head, wherein a gapped bar made of ferrite and having a coil turn hole and a magnetic gap is subjected to a laser machining to form a track, the improvement comprising subjecting at least a portion, which defines the track width, of the gapped bar to a laser-induced etching under a condition that a laser light having a power of 50-1,100 mW and a focused beam diameter of not larger than 20 μm is irradiated to at least the track width-defining portion at a scanning speed of 2-110 μm/sec in a halogen gas- or halide gas-containing atmosphere kept to a gas pressure of 10-200 Torr, to form a groove having a surface roughness of not larger than 2 μm in the side wall for defining the track width.
Claim 2
Dependent Claim
137 words
In a method of producing a core for magnetic head, wherein a gapped bar made of ferrite and having a coil turn hole and a magnetic gap is subjected to a laser machining to form a track, the improvement comprising subjecting at least a portion, which defines the track width, of the gapped bar to a laser-induced etching under a condition that a laser light having a power of 50-1,100 mW and a focused beam diameter of not larger than 20 μm is irradiated to at least the track width-defining portion at a scanning speed of 2-110 μm/sec in a halogen gas- or halide gas-containing atmosphere kept to a gas pressure of 10-200 Torr, to form a groove having a surface roughness of not larger than 2 μm in the side wall for defining the track width.
Claim 3
Dependent Claim
13 words
A method according to claim 1, wherein the halide gas is carbon tetrachloride.
Claim 4
Dependent Claim
14 words
A method according to claim 1, wherein the laser light is Ar ion laser.
Claim 5
Dependent Claim
42 words
A method according to claim 1, wherein the portion other than the track width-defining portion is etched by irradiating to the portion a laser light having a power of 700-1,500 mW at a scanning speed of 100-700 μm/sec in the laser-induced etching.
Claim 6
Dependent Claim
43 words
A method according to claim 1, wherein the portion other than the track width-defining portion is etched off by irradiating a laser light to the portion in an etching solution containing acid, such as phosphoric acid, or containing alkali, such as potassium hydroxide.
Claim 7
Dependent Claim
31 words
A method according to claim 1, wherein the portion other than the track width-defining portion is eliminated by the YAG laser machining in the air, ultrasonic wave machining or discharge machining.
Claim 8
Dependent Claim
54 words
A method according to claim 1, wherein a gapped bar having a coil turn hole having a width equal to or somewhat larger than the width of a portion to be etched off is used, which portion is the whole of a track width-defining portion and a portion other than the track width-defining portion.
Claim 9
Dependent Claim
43 words
A method according to claim 7, wherein a groove, which penetrates up to the coil turn hole, is formed along the profile of the portion to be etched off, and the portion is scooped out from the gapped bar to form a track.
Claim 10
Dependent Claim
31 words
A method according to claim 1, wherein the groove is filled with a non-magnetic material, such as glass, and then the gapped bar is cut into cores having a predetermined width.
References Cited (Backward Citations)
US4100584A
Cited
US4693779A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-06-21 | 1991-12-21 | 1992-06-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-06-21 | 1995-12-21 | 1996-06-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-06-21 | 1999-12-21 | 2000-06-21 | $7700.00 | Window Closed / Lapsed |