JP2813195B2 - Electromagnet for overwriting - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an overwriting electromagnet used for overwriting a magneto-optical storage element.

[Conventional technology]

Conventionally, in a magneto-optical storage element that performs magnetic recording in a state where a recording medium is heated by a laser beam or the like, when performing re-recording on a recorded medium, the recorded information is temporarily rewritten before re-recording. I was trying to erase it. However, in this case, there is a disadvantage that an unnecessary erasing step is required for a recording medium such as a magnetic disk.

Therefore, in recent years, research on overwriting, in which a recorded medium is re-recorded without going through an erasing step, has been advanced. As such an overwriting method, a so-called magnetic field modulation method in which an electromagnet is used as a magnetic head and the direction of a magnetic field is reversed according to information to be recorded, is considered promising.

By the way, as the above-mentioned electromagnet, a winding type is conventionally used (see Japanese Patent Application Laid-Open No. 62-279504). However, in this case, the overwriting is performed because the switching frequency in the direction of the magnetic field is relatively low. Is difficult to achieve, and it is difficult to efficiently apply a magnetic field only to a specific area on the recording medium, so that power consumption is increased.

Therefore, a thin-film coil formed on a base has been proposed as an electromagnet for overwriting that can be switched at high speed (Optical Memory Symposium '88 held at Casals Hall, Tokyo, September 20, 1988). (See “High-speed overwrite in magneto-optical recording (Prepared and reported by Sony Corporation, Optical Disk Drive Division)”).

[Problems to be solved by the invention]

An object of the present invention is to provide an overwriting electromagnet capable of further improving the switching frequency by improving the above-described overwriting electromagnet.

[Means for solving the problem]

According to a first aspect of the present invention, there is provided an overwriting electromagnet for use in recording information on a magneto-optical storage element, wherein the overwriting electromagnet has a good thermal conductivity on a substrate. At least two thin-film coils are formed via a film.

According to a second aspect of the present invention, there is provided an overwrite electromagnet according to the first aspect, wherein the dielectric film is made of AlN. is there.

According to a third aspect of the present invention, there is provided an overwrite electromagnet according to the first aspect of the present invention, wherein the dielectric film is a conductive film for radiating heat of the thin film coil. A heat film and a sandwiching dielectric film sandwiching the heat transfer film from both sides and insulating at least two thin film coils from each other are provided.

[Action]

According to the first aspect of the present invention, since the thin-film coil is formed in at least two layers via the dielectric film having good heat conductivity, the temperature rise of the overwriting electromagnet due to the heat generated from the thin-film coil is suppressed. The impedance of the thin-film coil can be reduced, thereby increasing the switching frequency. Further, since the thin-film coil is formed in multiple layers, the strength of the magnetic field can be increased. Further, the size of the electromagnet can be reduced, so that a magnetic field can be efficiently applied only to a specific area on the recording medium.

According to the invention of claim 2, since AlN having good thermal conductivity is used as the dielectric film, it is possible to suppress a temperature rise of the overwriting electromagnet due to heat generated from the thin film coil.

According to the invention of claim 3, since the dielectric film has a structure in which both sides of the heat transfer film are sandwiched by the sandwiched dielectric films, the heat transfer film
While the heat of the thin film coil can be radiated by using a metal such as Cu, the insulation between the thin film coils can be performed by the sandwiching dielectric film.

Embodiment 1 An embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

FIG. 3 shows a magneto-optical disk as a magneto-optical storage element
1 shows a recording / reproducing apparatus for recording / reproducing and erasing information from / to 11 The recording / reproducing apparatus includes a motor 12 for rotating the magneto-optical disk 11 and an objective lens 16 for driving the objective lens 16 up and down and right and left so that the light spot of the light beam 17 follows a track (not shown) of the magneto-optical disk 11. A lens driving device 14, an optical head 13 for guiding a light beam 17 emitted from a laser light source 13a to a recording layer 11a of a magneto-optical disk 11 via a mirror 13b, and a recording layer for applying a constant magnetic field during initial recording and overwriting of information. An overwrite electromagnet 5 to be applied to 11a, a linear motor 18 for moving the optical head 13 and the objective lens driving device 14 to access a target track at high speed, and the like are provided.

As shown in FIG. 2, the overwriting electromagnet 5 is provided on a base 1 as a base made of ferrite.
Is formed.

The thin film coil 2 will be described in more detail. As shown in FIG. 1, the base 1 is provided with an annular groove 1a having both sides formed in a tapered shape. A first dielectric film 3 made of, for example, AlN is formed on the surface of the base 1 including the inside of the annular groove 1a.
Are formed. On the first dielectric film 3, for example,
The first layer thin film coil 2a made of AuCr is formed in a plurality of turns.

In the same manner as described above, a second dielectric film 4 made of, for example, AlN is formed on the thin film coil 2a, and a second layer made of, for example, AuCr is formed on the second dielectric film 4. The thin film coil 2b is formed in a plurality of turns in parallel with the thin film coil 2a.

The first and second dielectric films 3 and 4 are formed by vapor deposition or sputtering, and the coils 2a and 2b of the first and second layers are formed by using photoresist in a process such as vapor deposition or sputtering. It is formed by combining the etching steps described above. The thickness of the first and second dielectric films 3 and 4 is, for example, about 100 to 1000 nm, respectively, and the thickness of the first and second layers of the coils 2a and 2b is, for example, 100 About 3000 nm.

In the above configuration, the first and second dielectric films 3 and 4
Is formed of AlN, the thermal conductivity of the dielectric films 3 and 4 is improved, so that the temperature rise of the overwriting electromagnet 5 due to heat generated from the thin film coils 2a and 2b can be suppressed.

 Here, Table 1 shows the thermal conductivity of various materials.

As is clear from Table 1, AlN has high thermal conductivity,
It is suitable as a material for the first and second dielectric films 3 and 4.

In the above-described embodiment, the first dielectric film 3 is formed between the base 1 and the thin-film coil 2a in order to enhance the thermal conductivity. Omitted, base 1
The thin-film coil 2a may be formed directly on top.

Further, the thin film coils 2a and 2b may be formed of, for example, Au other than AuCr, and the thin film coils may be formed in three or more layers.

Second Embodiment Next, a second embodiment will be described.

In this second embodiment, as shown in FIG. 4, the first and second dielectric films 3 and 4 in the first embodiment are sandwiched between both sides of a heat transfer film 6 made of Cu and made of SiO ₂ respectively. Dielectric film 7
· It has a three-layer structure sandwiched by 7.

In this case, the heat transfer film 6 mainly plays a role of radiating heat of the thin film coils 2a and 2b, and the sandwiching dielectric films 7 play a role of mainly insulating the thin film coils 2a and 2b.

In addition, as the heat transfer film 6, besides Cu, for example, Al, A
g, Au, AuCr, etc. can be used.

On the other hand, as the sandwiching dielectric films 7, in addition to SiO ₂ , for example, SiN, TiO ₂ , Al ₂ O ₃ , SiNO, AlNO, AlSiN or some of them contained Y, Ti, Ta, Ni, etc. Things can be used.

〔The invention's effect〕

As described above, the overwrite electromagnet according to the first aspect of the present invention is an overwrite electromagnet used for recording information on a magneto-optical storage element, via a dielectric film having good thermal conductivity on a base. In this configuration, at least two thin film coils are formed.

As a result, since the thin film coil is formed in two or more layers via a dielectric film having good thermal conductivity, the impedance of the thin film coil is reduced while suppressing the temperature rise of the overwriting electromagnet due to the heat generated from the thin film coil. As a result, the switching frequency can be increased.

Further, since the thin-film coil is formed in multiple layers, the strength of the magnetic field can be increased, and therefore, recording can be performed even when the recording medium is at a relatively low temperature. It will contribute.

Further, since the size of the electromagnet can be reduced and a magnetic field can be efficiently applied only to the characteristic area on the recording medium, it is advantageous in suppressing power consumption.

As described above, the overwriting electromagnet according to the second aspect of the present invention is the overwriting electromagnet according to the first aspect of the present invention, wherein the dielectric film is made of AlN.

Thus, since AlN having good thermal conductivity is used as the dielectric film, the temperature rise of the overwriting electromagnet due to heat generated from the thin film coil can be suppressed.

As described above, the overwriting electromagnet according to the third aspect of the present invention is the overwriting electromagnet according to the first aspect of the present invention, wherein the dielectric film includes a heat transfer film that radiates heat of the thin film coil; The heat transfer film is sandwiched from both sides, and at least two layers of the thin film coil are insulated from each other.

As a result, since the dielectric film has a structure in which both sides of the heat transfer film are sandwiched by the sandwiched dielectric films, the heat of the thin film coil can be radiated by using a metal such as Cu for the heat transfer film, while the heat transfer film is sandwiched. Insulation between the thin film coils can be performed by the dielectric film.

[Brief description of the drawings]

1 to 3 show an embodiment of the present invention. FIG. 1 is a longitudinal sectional view of an electromagnet for overwriting. FIG. 2 is a schematic longitudinal sectional view of the overwriting electromagnet. FIG. 3 is an explanatory diagram of a recording / reproducing apparatus for recording / reproducing on / from a magneto-optical disk. FIG. 4 is a longitudinal sectional view showing a detailed structure of a dielectric film in an electromagnet for overwriting according to another embodiment of the present invention. 1 is a base (substrate), 2a and 2b are thin-film coils, 3 and 4 are first
The second dielectric film 11 is a magneto-optical disk (magneto-optical storage element).

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Junichiro Nakayama 22-22, Nagaikecho, Abeno-ku, Osaka-shi, Osaka Within Sharp Corporation (72) Inventor Akira Takahashi 22-22, Nagaikecho, Abeno-ku, Osaka-shi, Osaka Sharp Corporation (56) References JP-A-55-125509 (JP, A) JP-A-1-194111 (JP, A) JP-A-2-235239 (JP, A) (58) Fields investigated (Int. ⁶ , DB name) G11B 5/02 G11B 11/10 H01F 7/20

Claims (3)

(57) [Claims] 1. An overwrite electromagnet used for recording information on a magneto-optical storage element, wherein at least two thin-film coils are formed on a base via a dielectric film having good thermal conductivity. Overwriting electromagnet. 2. The overwrite electromagnet according to claim 1, wherein said dielectric film is made of AlN. 3. The dielectric film includes a heat transfer film for radiating heat of the thin film coil, and a sandwich dielectric film sandwiching the heat transfer film from both sides and insulating at least two thin film coils from each other. The electromagnet for overwriting according to claim 1, comprising: