EP0091812A1
Expired / Lapsed
EP
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A playback head for perpendicular magnetic recordings
Assignee: Panasonic Holdings Corp
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Filing: 1983-04-11
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Granted: —
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Expires: 2003-04-11
Abstract
Abstract A magneto-resitive playback head (35) and a recording and reproducing device for reproducing a recording signal from a double-layered film type perpendicular magnetic recording medium (2, 3, 4). The playback head includes a magneto-resistive element (11) included in high-permeability thin films including such at least one film and having one end portion facing the recording medium. The magneto-resistive element exhibits a magneto-resistance effect responsive to magnetic fluxes generated from signal magnetization in the recording medium. The head also includes electrodes (12, 13) for supplying an electric current longitudinally of the magneto-resistive element, and high-permeability members (8) for introducing the signal magnetic fluxes passed through the magneto-resistive element again to the recording medium. A magnetic recording and reproducing device comprises the playback head (35), a thin film magnetic recording head (34), a recording circuit (331, a playback circuit (36), and a driving circuit (32) which gives a relative motion between the medium and the heads.
Inventors
- 👤 Kenji Kanai
- 👤 Seishi Sasaki
- 👤 Ken Takahashi
- 👤 Ryuji Sugita
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-04 01:54
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/127; G11B5/33; G11B5/39; G11B5/3903; G11B5/3906; G11B5/3916; G11B5/3919; G11B5/1278; G11B5/399; G11B5/40
Claims Analysis
Total Claims: 35
Claim 1
Independent Claim
155 words
rA magnetic playback head for use with a double layered perpendicular magnetic recording medium including a layer (3) of high permeability material disposed on a base film (4), and a layer (2) of high coercive material with axis of easy magnetization in the direction of its thickness disposed on the high permeability layer; comprising a magnetic thin film (11) placed vertically to said recording medium, which comprises a magneto-resistive thin film which responds to signal flux from said recording medium, whose one end faces said recording medium, current supplying means (12, 13) to said magneto- resistive element, a high permeability core (8) which faces said recording medium and said thin film and which returns the flux from said magneto-resistive thin film to said recording medium, a magnetically separating member (9) which lies between said high permeability core and said thin film, whose one end faces said recording medium at the side of said recording medium.
Claim 2
Dependent Claim
155 words
rA magnetic playback head for use with a double layered perpendicular magnetic recording medium including a layer (3) of high permeability material disposed on a base film (4), and a layer (2) of high coercive material with axis of easy magnetization in the direction of its thickness disposed on the high permeability layer; comprising a magnetic thin film (11) placed vertically to said recording medium, which comprises a magneto-resistive thin film which responds to signal flux from said recording medium, whose one end faces said recording medium, current supplying means (12, 13) to said magneto- resistive element, a high permeability core (8) which faces said recording medium and said thin film and which returns the flux from said magneto-resistive thin film to said recording medium, a magnetically separating member (9) which lies between said high permeability core and said thin film, whose one end faces said recording medium at the side of said recording medium.
Claim 3
Dependent Claim
24 words
A magnetic playback head according to claim 1, wherein another end of said magnetic thin film is magnetically coupled with said high permeability core.
Claim 4
Dependent Claim
37 words
A magnetic playback head according to claim 1, wherein said high permeability core (8) is magnetic substrate and wherein said magnetic separating member is a groove (9) filled by non magnetic material (10) on said magnetic substrate.
Claim 5
Dependent Claim
54 words
A magnetic playback head according to claim 1, wherein said high permeability core (8) is a magnetic substrate, and wherein said magnetically separating member is non magnetic layer (18) on a flat face of said magnetic substrate, and wherein said magnetic thin film is laid over said magnetic substrate and said non magnetic layer.
Claim 6
Dependent Claim
70 words
A magnetic playback head according to claimn 1, wherein said magnetic separating member is non magnetic layer (18) on said magnetic substrate, and wherein said high permeability core is constructd by said magnetic substrate (18) and high permeability layer (19) deposited on said magnetic substrate contact with and on opposite side of said non magnetic layer and whose thickness is almost equal to that of said non magnetic layer (18).
Claim 7
Dependent Claim
71 words
A magnetic playback head according to claim 1, wherein the distance between said high permeability core and said magnetic thin film whose one end faces said recording medium at the surface which faces said recording medium is large enough compared to wavelength recorded on said recording medium and the thickness of said magnetic thin film whose one end faces is small enough compared to said recording wavlength on said recording medium.
Claim 8
Dependent Claim
56 words
A magnetic playback head according to claim 2, wherein said another end of said magnetic thin film is overlapped with said high permeability core and the relation of the overlapped area of said thin film with said high permeability core Sl, and the other area of said thin film S2 is 0.1 < S1/S2 < 0.6.
Claim 9
Dependent Claim
23 words
A magnetic playback head according to claim 1, further comprising means (25, 26) for applying magnetic bias field to said magneto-resistive thin film.
Claim 10
Dependent Claim
49 words
A magnetic playback head according to claim 8, wherein means for applying magnetic bias field is high electric conductivity thin film (25) disposed between said magnetic separating member and said magneto-resistive thin film, and further comprising second current supplying means (22, 23) to said high electric conductivity thin film.
Claim 11
Dependent Claim
46 words
A magnetic playback head according to claim 8, wherein said means for applying bias field is a high electric conductivity member and which is molded in said magnetic separating member and further comprising second electric current supplying means (22, 23) to said high electric conductivity member.
Claim 12
Dependent Claim
33 words
A magnetic playback head according to claim 1, wherein the direction of the magnetic easy axis of said magneto-resistive thin film is different from that of electric current in said magneto-resistive thin film.
Claim 13
Dependent Claim
42 words
A magnetic playback head according to claim 1, further comprising a foundation (41) of said magneto-resitive thin film, and the foundation has grooves of a constant period in the different direction from that of the electric current in said magneto-resistive thin film.
Claim 14
Dependent Claim
159 words
A magnetic playback head for use with a double layered perpendicular magnetic recording medium including a layer of high permeability material disposed on a base film, and a layer of high coercive material with axis of easy magnetization in the direction of its thickness disposed on the high permeability layer; comprising magnetic thin films placed vertically to said recording medium, which comprise a magneto-resistive thin film (11) which responds to signal flux from said recording medium and a high permeability thin film (21) whose one end faces said recording medium, current supplying means (12, 13) to said magneto- resistive thin film, a high permeability core (8) which faces to said recording medium and said magneto-resistive thin film and which returns flux from said magneto-resitive thin film to said recording medium, a magnetically separating member which lies between said high permeability core and said thin films whose one end faces said recording medium at the side of said recording medium.
Claim 15
Dependent Claim
159 words
A magnetic playback head for use with a double layered perpendicular magnetic recording medium including a layer of high permeability material disposed on a base film, and a layer of high coercive material with axis of easy magnetization in the direction of its thickness disposed on the high permeability layer; comprising magnetic thin films placed vertically to said recording medium, which comprise a magneto-resistive thin film (11) which responds to signal flux from said recording medium and a high permeability thin film (21) whose one end faces said recording medium, current supplying means (12, 13) to said magneto- resistive thin film, a high permeability core (8) which faces to said recording medium and said magneto-resistive thin film and which returns flux from said magneto-resitive thin film to said recording medium, a magnetically separating member which lies between said high permeability core and said thin films whose one end faces said recording medium at the side of said recording medium.
Claim 16
Dependent Claim
99 words
A magnetic playback head according to claim 13, wherein said magnetic thin films comprise a high permeability thin film for first magnetic thin film and a magneto-resistive thin film for second magnetic thin film, and one end of said first magnetic thin film faces said recording medium, and another end of said first magnetic thin film is magnetically coupled with one end of said second thin film and another end of second magnetic thin film is magnetically coupled with said high permeability core, and further comprising an insulating thin film (22) between said first and second magnetic thin film.
Claim 17
Dependent Claim
33 words
A magnetic playback head according to claim 13, wherein said high permeability core is magnetic substrate and wherein said magnetic separating member is a groove filled by non-magnetic material on said magnetic substrate.
Claim 18
Dependent Claim
53 words
A magnetic playback head according to claim 13, wherein said high permeability core is a magnetic substrate, and wherein said magnetically separating member is non-magnetic layer on a flat face of said magnetic substrate, and wherein said magnetic thin film or thin films are laid over said magnetic substate and said non-magnetic layer.
Claim 19
Dependent Claim
63 words
A magnetic playback head according to claim 13, wherein said magnetic separating member is non-magnetic layer on said magnetic substrate, and wherein said high permeability core is constructed by said magnetic substrate and high permeability layer deposited on said magnetic substrate contact with an on opposite side of said non-magnetic layer and whose thickness is almost equal to that of said non-magnetic layer.
Claim 20
Dependent Claim
77 words
A magnetic playback head according to claim 13, wherein the distance between said high permeability core and said high permeability thin film whose one end faces to said recording medium at the surface which faces said recording medium is large enough compared to recorded wavelength on said recording medium and the thickness of said high permeability thin film whose one end faces said recording medium is small enough compared to said recording wavelength on said recording medium.
Claim 21
Dependent Claim
22 words
19 A magnetic playback head according to claim 13, further comprising means for applying magnetic bias field to said magneto-resistive thin film.
Claim 22
Dependent Claim
48 words
A magnetic playback head according to claim 19, wherein means for applying magnetic bias field is a high electric conductivity thin film (25) disposed between said magnetic separating member and said magneto-resistive thin film, and further comprising second current supplying means to said high electric conductivity thin film.
Claim 23
Dependent Claim
45 words
A magnetic playback head according to claim 19, wherein said means for applying bias field is a high electric conductivity member (26) and which is molded in said magnetic separating member and further comprising second electric current supplying means to said high electric conductivity member.
Claim 24
Dependent Claim
32 words
A magnetic playback head according to claim 13, wherein the direction of the easy magnetization of said magneto-resistive thin film is different from that of electric current in said magneto-resistive thin film.
Claim 25
Dependent Claim
43 words
A magnetic playback head according to claim 13, further comprising a foundation of said magneto resistive thin film, and the foundation has grooves of a constant period in the different direction from that of the electric current in said magneto resistive thin film.
Claim 26
Dependent Claim
47 words
A magnetic playback head according to claim 14, wherein the relation of the thickness of first thin film tl and that of second thin film t2 and the maximum flux density of fist thin film Bml and that of second thin film Bm2 is tlBml > t2Bm2.
Claim 27
Dependent Claim
65 words
A magnetic playback head according to claim 14, said another end of second magnetic thin film is overlapped with said high permeability core and the relation of the overlapped area of said second thin film with said high permeability core Sl, and the area of the second magnetic thin film which is not overlapped with other magnetic members S2, is 0.1 < S1/S2 < 0.6.
Claim 28
Dependent Claim
32 words
A magnetic playback head according to claim 25, wherein the relation of S2 and the overlapped area of the first and second magnetic thin film S3 is 0.1 < S3/S2 < 0.5.
Claim 29
Dependent Claim
170 words
A magnetic playback head for use with a double layered perpendicular magnetic recording medium including a layer of high permeability material disposed on a base film, and a layer of high coercive material with axis of easy magnetization in the direction of its thickness disposed on the high permeability layer; comprising magnetic thin films placed vertically to said recording medium, which comprise a magneto-resistive thin film which responds to signal flux from said recording medium and a high permeability thin film whose one end faces said recording medium, current supplying means to said magneto-resistive element, a high permeability core which faces said recording medium and said magneto-resistive thin film and which returns the flux from said magneto-resistive thin film to said recording medium, a magnetically separating member which lies between said high permeability core and said thin films whose one end faces said recording medium at the side of said recording medium, a protection member (24) of non-magnetic material which lies on said magnetic thin film or magnetic thin films.
Claim 30
Dependent Claim
170 words
A magnetic playback head for use with a double layered perpendicular magnetic recording medium including a layer of high permeability material disposed on a base film, and a layer of high coercive material with axis of easy magnetization in the direction of its thickness disposed on the high permeability layer; comprising magnetic thin films placed vertically to said recording medium, which comprise a magneto-resistive thin film which responds to signal flux from said recording medium and a high permeability thin film whose one end faces said recording medium, current supplying means to said magneto-resistive element, a high permeability core which faces said recording medium and said magneto-resistive thin film and which returns the flux from said magneto-resistive thin film to said recording medium, a magnetically separating member which lies between said high permeability core and said thin films whose one end faces said recording medium at the side of said recording medium, a protection member (24) of non-magnetic material which lies on said magnetic thin film or magnetic thin films.
Claim 31
Dependent Claim
24 words
A magnetic playback head according to claim 27, wherein the hardness of said protection member (24) and said magnetic separating member are nearly equal.
Claim 32
Dependent Claim
22 words
A magnetic playback head according to claim 27, wherein said protection member and said magnetic separating member are made of same material.
Claim 33
Dependent Claim
38 words
A magnetic playback head according to claim 27, wherein said high permeability core is made of ferrite and the hardness of said protection member and said magnetic separating member are nearly equal or higher than that of ferrite.
Claim 34
Dependent Claim
168 words
A magnetic recording and reproducing device comprising, perpendicular magnetic recording medium including a layer of high permeability material disposed on a base film, and a layer of high coercive material with axis of easy magnetization in the dirction of its thickness disposed on the high permeability layer; a magnetic thin film placed vertically to said recording medium, which comprises a magneto-resistive thin film which responds to signal flux from said recording medium whose one end faces said recording medium, current supplying means to said magneto-resistive element, a high permeability core which faces said recording medium and said thin film and which returns the flux from said magneto-resistive thin film to said recording medium, a magnetically separating member which lies between said high permeability core and said thin film whose one end faces to said recording medium at the side of said recording medium, a thin film magnetic recording head, a recording circuit, a playback circuit, driving means which give a relative motion between said medium and said heads.
Claim 35
Dependent Claim
168 words
A magnetic recording and reproducing device comprising, perpendicular magnetic recording medium including a layer of high permeability material disposed on a base film, and a layer of high coercive material with axis of easy magnetization in the dirction of its thickness disposed on the high permeability layer; a magnetic thin film placed vertically to said recording medium, which comprises a magneto-resistive thin film which responds to signal flux from said recording medium whose one end faces said recording medium, current supplying means to said magneto-resistive element, a high permeability core which faces said recording medium and said thin film and which returns the flux from said magneto-resistive thin film to said recording medium, a magnetically separating member which lies between said high permeability core and said thin film whose one end faces to said recording medium at the side of said recording medium, a thin film magnetic recording head, a recording circuit, a playback circuit, driving means which give a relative motion between said medium and said heads.
References Cited (Backward Citations)
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