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Magneto-optical head having heat sink layer

a heat sink layer and magnetic technology, applied in the direction of instruments, disposition/mounting of heads, light beam reproducing, etc., can solve the problems of deteriorating optical characteristics of lenses, deteriorating magnetic characteristics, and still remaining problems

Inactive Publication Date: 2004-12-09
HITACHT MAXELL LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0018] In the magneto-optical head according to the present invention, the heat-releasing member is provided on the second surface. Accordingly, even when the magnetic coil is heated by the radiation of the light beam, the heat is not released to the first surface side of the substrate on which the lens is provided. Therefore, it is possible to avoid the thermal expansion of the lens, especially of the objective lens having high NA of 0.6.ltoreq.NA, and it is possible to appropriately maintain the optical characteristics of the lens. On the other hand, the heat-releasing member, which is provided on the second surface, makes it possible to release the heat generated by the magnetic coil and the vicinity thereof, to the space between the magneto-optical head and the information-recording medium. Especially, the information-recording medium usually makes the rotating movement at a linear velocity of not less than 1 m / s with respect to the magneto-optical head. Therefore, the heat-releasing member is efficiently cooled by the air stream which is generated by the rotating movement.
[0046] In the magneto-optical head described above, the optical axes of the first lens and the second lens can be correctly adjusted by relatively moving the first lens holder with respect to the second lens holder by using the first actuator. Therefore, it is possible to avoid any occurrence of the wave front aberration even when a lens having high NA is used for the second lens. The discrepancy between the optical axes of the first lens and the second lens can be detected by detecting a reproduced signal from the information-recording medium while relatively moving the first lens holder with respect to the second lens holder by the first actuator.

Problems solved by technology

Even if the film surface incidence system is adopted as described above, various problems still remain when the objective lens having high NA is used.
However, the magnetic characteristics are deteriorated especially when the recording is performed by applying a modulated magnetic field having a high frequency, because the magnetic coil is heated by the radiated light beam.
However, if the heat is conducted to the objective lens, a problem arises such that the optical characteristics of the lens are deteriorated due to the thermal expansion of the lens.
When the lenses each having high NA are used for the objective lenses, the wave front aberration readily tends to appear due to any discrepancy between the optical axes of the lenses.
It was revealed that the error rate was at a level at which the reproduction channel sufficiently functioned.
It was revealed that the error rate was at a level at which the reproduction channel sufficiently functioned.

Method used

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  • Magneto-optical head having heat sink layer
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  • Magneto-optical head having heat sink layer

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fifth embodiment

[0122] The fifth embodiment is a modified embodiment of the fourth embodiment, which will be explained with reference to FIGS. 17 to 20. In this embodiment, a magneto-optical head was produced by providing a protective pad 91 as shown in FIG. 17 in place of the projection 70 of the magnetic coil substrate produced in the fourth embodiment. The magnetic coil substrate as described above can be produced as follows. In the process steps shown in FIGS. 6(a) and 6(b), the reactive etching is performed while providing the mask not only for the protruding section 50 of the substrate 3 but also for an outer circumferential portion corresponding to the projection 70. Accordingly, the projection 70 can be formed to have the same height as that of the protruding section 50. The protective pad 91 may be bonded onto the projection 70. The protective pad can be formed with resin as described later on. As shown in FIG. 18, for example, a frame-type pad 91, which was provided on the entire outer ci...

sixth embodiment

[0126] FIG. 21 shows a modified embodiment of the first embodiment. A magnetic coil substrate shown in FIG. 21 is produced in the same manner as in the first embodiment except that the film thickness of a heat sink layer 800 is thicker than that in the first embodiment, and the lower end of the heat sink layer 800 is disposed more closely to the disk side. The heat, which is generated from the magnetic coil 15 and which is transmitted to the heat sink layer, is readily released to the space between the disk and the substrate 3, because the heat sink layer 800 is disposed more closely to the disk side. Therefore, the heat-releasing effect of the heat sink layer is improved. The heat sink layer may further extend downwardly to make contact with the protective film 17. Alternatively, the heat sink layer may be exposed to the disk side without providing the protective film 17 partially. By doing so, the heat-releasing effect of the heat sink layer can be further improved.

seventh embodiment

[0127] In this embodiment, a magnetic coil substrate was formed in the same manner as in the first embodiment except that a magnetic coil 600 was formed to have an elliptic configuration as shown in FIG. 26. A magneto-optical head was produced with the magnetic coil substrate. The elliptic magnetic coil can be formed with ease by exposing the photoresist to the light with an elliptic helical pattern as a photomask in the step for forming the coil shown in FIG. 6(d).

[0128] The reason why the magnetic coil 600 was formed to have the elliptic configuration is as follows. That is, it is necessary to perform the tracking for the disk when information is recorded or reproduced on the magneto-optical disk by using the magneto-optical head. The tracking is performed by operating a rotary actuator for supporting a head and a galvano-mirror provided for a fixed optical system (see FIG. 25) installed with a laser light source and a detector by the aid of an arm. The light beam, which is reflec...

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Abstract

A magneto-optical recording head comprises a magnetic coil formed on a lower surface of a transparent substrate opposed to a magneto-optical disk. A heat sink layer is provided at the outside of the magnetic coil on the lower surface. An objective lens is supported on an upper surface of the transparent substrate. The heat, which is generated by the magnetic coil, is released via the heat sink layer to the space between the magneto-optical disk and the substrate. The release of the heat is facilitated by the air stream which is generated by the rotation of the magneto-optical disk. The heat can be effectively released from the magnetic coil without inhibiting optical characteristics of the objective lens.

Description

[0001] This is a Divisional of application Ser. No. 09 / 973,021, filed Oct. 10, 2001. The entire disclosure of the prior application is hereby incorporated by reference herein in its entirety.[0002] 1. Field of the Invention[0003] The present invention relates to a magneto-optical recording apparatus for recording information on a magneto-optical recording medium with an objective lens having high NA. The present invention also relates to a magneto-optical head to be used for the magneto-optical recording apparatus.[0004] 2. Description of Related Art[0005] In recent years, in response to the advance of multimedia, the optical recording medium has been used, on which a large amount of data can be recorded at a high density, and recording and reproduction can be performed at a high speed. Such an optical recording medium includes read-only media such as compact disks on which information is previously recorded as pits on the disk during formation of the disk, write-once media such as ...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): G11B7/09G11B7/12G11B7/135G11B11/105
CPCG11B7/0937G11B7/1201G11B7/121G11B7/122G11B7/1374G11B7/13925G11B11/10534G11B11/10543G11B11/10554G11B11/10576G11B11/1058G11B2007/13727
Inventor ISHIZAKI, OSAMUSHIMAZAKI, KATSUSUKEAWANO, HIROYUKITAMURA, REIJIMARO, TSUYOSHISUGIYAMA, TOSHINORI
Owner HITACHT MAXELL LTD
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