Dynamic magnetic information storage or retrieval – Head – Coil
Patent
1998-08-17
2000-12-19
Renner, Craig A.
Dynamic magnetic information storage or retrieval
Head
Coil
2960323, G11B 517
Patent
active
061634352
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
The present invention relates to a vertical magnetic head with integrated coil and its manufacturing process.
It finds privileged application in video recording by the general public. But it may also be used in other areas, such as data backup or computer memories.
2. State of the Prior Art
A magnetic recording medium for video recording, data backup or computer memory comprises numerous tracks on which information is written in the form of magnetic fields.
To increase information density, not only can the amount of information per unit length be increased, but also the number of tracks. To achieve this purpose, track width is reduced and, simultaneously, the distance between them is reduced until the tracks abut one another.
To avoid any crosstalk problems on reading, the information on two adjacent tracks is written at opposite angles. The head angle must be most precise (for example 20.+-.0.150.degree. in the new so-called DVC standard for <<Digital Video Cassette >>).
To meet these requirements, so-called <<sandwich >> heads can be currently found on the market of which an example of embodiment is illustrated in FIG. 1 appended hereto. The head shown comprises a substrate 2 carrying a magnetic circuit 4 made up of a magnetic layer placed on the top surface of the substrate, this circuit having two polar parts 5 and 7 at the front separated by an air gap 6 which is formed by a nonmagnetic spacer. This head also comprises, above the magnetic circuit, a nonmagnetic superstrate 2'. An opening 8 is pierced through the whole unit to allow the passage of a conductor coil 9 surrounding the magnetic circuit.
The head shown in FIG. 1 is intended to co-operate with a recording medium S oriented perpendicular to the substrate (in other words parallel to the latter's edge).
Such heads may be described as <<vertical >> in the sense that the active surface is perpendicular to the general surface of the substrate.
The width of the air gap, called 1, is calculated perpendicular to the substrate (parallel to the recording medium). This width 1 substantially corresponds to the respective width of the tracks in the medium. The length of the air gap, called L, is calculated in the direction of the relative movement of the head and recording medium. The height of the air gap, called h, is calculated parallel to the surface of the substrate carrying the magnetic circuit.
As soon as track width becomes narrow (less than approximately 10 micrometers), these heads become very difficult to fabricate (problems relating to precision alignment of the two polar parts during glass welding, low efficiency due to magnetic circuit length, difficult coil production, which is an added part and cannot be adapted easily to a package production process etc.)
The abstract of Japanese patent, vol. 13, n.degree.98 (P-840) (3446) of Mar. 8, 1989, describes a different magnetic head with planar coiling. This head is shown in FIG. 2 appended hereto. It comprises two polar parts 12a, 12b separated by an air gap 13, a twin spiral coil 14a, 14b placed over the two limbs of the magnetic circuit, two connection pads 15a, 15b and a magnetic bridge 15 closing the magnetic circuit.
This head still has disadvantages connected firstly with its coil structure which is long and therefore resistant producing thermal noise and, secondly with its magnetic circuit which is relatively long and therefore has reduced efficiency.
EP-A-0,467,263 discloses a head which partly avoids these drawbacks. This type of head can be seen in appended FIGS. 3 and 4. They show a nonmagnetic substrate 21, a first insulating layer 22, a second insulating layer 29, a magnetic circuit 30, a conductor coil 38 of solenoid type wound around the magnetic circuit, electric connection strips 33 and connection pads 34.
FIG. 4 also shows the two front polar parts 25 and 27 separated by an air gap g. Also, an insulating layer 35 covering the entire unit and a protective layer 36 or superstrate complete the unit and make the co
REFERENCES:
patent: 4743988 (1988-05-01), Sato et al.
patent: 4853815 (1989-08-01), Diepers
patent: 5566442 (1996-10-01), Gaud et al.
patent: 5604973 (1997-02-01), Gaud et al.
patent: 5668689 (1997-09-01), Schultz et al.
patent: 5883760 (1999-03-01), Yamada et al.
Thin Film Type Laminated Head, IBM Technical Disclosure Bulletin, vol. 37, No. 12, pp. 77-79, Dec. 1994.
Di Gioia Michel
Gaud Pierre
Sibuet Henri
Commissariat a l''Energie Atomique
Renner Craig A.
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