JP2854882B2 - Magneto-optical recording apparatus and magneto-optical recording method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magneto-optical recording device and a magneto-optical recording method capable of overwriting information on a magneto-optical recording medium by overwriting.

[Prior Art] Conventionally, a method as shown in FIG. 3 has been proposed as a magneto-optical recording apparatus made to enable rewriting of information by overwriting.

In FIG. 3, reference numeral 1 denotes a magneto-optical disk. In this conventional example, this magneto-optical disk is constituted by applying a perpendicular magnetization film 3 to a glass substrate 2. The magneto-optical disk 1 is rotated about a central axis 0-0 '.

Reference numeral 4 denotes an optical head for irradiating the perpendicular magnetic film 3 of the magneto-optical disk 1 with laser light. The optical head 4 has a semiconductor laser 5 and a condenser lens 6 as main components, has a function of always focusing a laser beam on the perpendicular magnetization film 3, and has a function in the radial direction of the magneto-optical disk 1. It is configured to be mobile. 7 is a magneto-optical disk 1
In contrast, the electromagnet applies a bias magnetic field to the perpendicular magnetization film 3 arranged so as to face the optical head 4. The electromagnet 7 is configured to move in the radial direction in conjunction with the optical head 4. The coil 8 connected to the magnetic field modulation circuit 9
Thus, a current for inverting the phase in accordance with the recording signal is supplied.

The magnetic field modulation circuit 9 operates according to a recording signal.
When the recording signal changes as shown in FIG. 4 (a), and in synchronism therewith, when the recording signal is "1", the direction of magnetization of the perpendicular magnetization film 3 becomes sufficiently upward in the laser beam irradiation state. It is configured such that the bias magnetic field strength (c) can be generated at a constant value, and when the recording signal is "0", the bias magnetic field strength (c) is equal and constant in the opposite direction to the case where the recording signal is "1". It is configured to operate. At this time, the laser beam from the optical head is continuously emitted in the recording state so that the laser beam intensity (b) becomes constant, and locally irradiates the perpendicular magnetization film 3 of the magneto-optical disk 1. The temperature of the perpendicular magnetization film at the irradiated portion is raised to a temperature higher than the Curie point.

In the magneto-optical recording apparatus configured as described above, for example, when a recording signal (a) as shown in FIG. 4 is supplied, the laser beam intensity (b) raises the perpendicular magnetization film 3 above the Curie point. Driven continuously with sufficient intensity _PW ,
Further, the bias magnetic field strength (c) is generated with a strength of ± H in synchronization with the recording signal (a). Therefore, the optical disk 1
In the perpendicular magnetization film 3, a recording pattern as schematically shown in FIG. 4D is formed. Note that, in this case, the white and oblique recording patterns indicate a state in which magnetization is upward and magnetization is downward, respectively.

In this conventional magneto-optical recording apparatus, the perpendicular magnetization film 3 of the magneto-optical disk 1 is continuously heated by a laser beam to the Curie point or higher and magnetized in the direction of a magnetic field modulated in accordance with a recording signal. regardless advance what information the perpendicular magnetic film 3 of the magnetic disk 1 is recorded, it is possible to new information recorded by overwriting.

[Problem to be Solved by the Invention] However, in the above-mentioned conventional example, there is a problem that a portion (pit edge 40) adjacent to the pit of the recording pattern as shown in FIG.

This occurs when the direction of the applied magnetic field is reversed,
This phenomenon occurs because the magnetization direction of the perpendicular magnetization film 3 becomes unstable in the transition region of the applied magnetic field.

Such an uneven state causes a rise in noise of a reproduced signal, and further, there is a problem that peak shift and increase in jitter are induced due to unclearness of a pit edge portion.

Means for Solving the Problems In view of the above problems, it is an object of the present invention to eliminate unevenness in the edge portion of a recording pit in a transition region of magnetic field modulation, and to provide a good reproduced signal with less noise, less peak shift and less jitter. It is an object of the present invention to provide a magneto-optical recording device and a magneto-optical recording method that can obtain the above.

An object of the present invention is to irradiate a condensed light to a magneto-optical recording medium having a perpendicular magnetic film, and to modulate a portion of the medium to which the light is irradiated according to a recording signal and to adjust a position of the perpendicular magnetic film. Magnetic field strength ± H sufficient to determine the direction of magnetization
Bias applying means for applying a bias magnetic field of
In a magneto-optical recording apparatus for recording information by forming recording pits magnetically, the intensity of a bias magnetic field to be applied is stronger at the front of the recording pits to be formed than at other areas in the recording pits, and This is achieved by a magneto-optical recording apparatus characterized by comprising bias magnetic field waveform adjusting means for setting a magnetic field strength ± Ha larger than a magnetic field strength ± H.

Further, an object of the present invention is to irradiate a condensed light on a magneto-optical recording medium having a perpendicular magnetic film, and to modulate a portion of the medium irradiated with the light in accordance with a recording signal, and to irradiate the perpendicular magnetic film with the light. In a magneto-optical recording method in which information is recorded by applying a bias magnetic field having a magnetic field strength ± H sufficient to determine the direction of magnetization of a magnetic field and magnetically forming a recording pit, at the front of the recording pit to be formed The intensity of the applied bias magnetic field is stronger than that of the other area in the recording pit, and the magnetic field strength ± Ha is larger than the magnetic field strength ± H.
This is achieved by a magneto-optical recording method characterized in that:

EXAMPLES Hereinafter, a magneto-optical recording device and a magneto-optical recording method of the present invention will be described in detail based on specific examples.

FIG. 1 shows an embodiment of the present invention. In FIG.
Is a magneto-optical disk on which a perpendicular magnetic film 3 is applied to a glass substrate or a plastic substrate 2 and a protective film 11 for protecting the perpendicular magnetic film 3 is applied; 4, an optical head comprising a semiconductor laser 5 and a lens 6; Denotes an electromagnet constituted by supplying a current to the coil 8. Reference numeral 10 denotes a bias magnetic field waveform adjusting circuit which is a means for increasing the intensity of a bias magnetic field applied in front of a recording pit to be formed as compared with other areas in the recording pit. The bias magnetic field waveform adjustment circuit 10 includes a front detection circuit 10a for a pit to be formed and a current control circuit 10b. The magneto-optical disk 1 is rotated about a central axis 0-0 'by a spindle motor (not shown).

The optical head 4 has an AF function for keeping the laser beam emitted from the semiconductor laser 4 always focused on the perpendicular magnetization film 3 and an AT function for following a track to be recorded or reproduced. The electromagnet 7 is arranged to face the position where the laser light is focused by the optical head 4, and can move in the radial direction of the optical disc 1 in conjunction with the optical head 4.

The operation of the above configuration will be described below with reference to the recording operation shown in FIG.

For example, when a recording signal is given as shown in (a), the laser light from the optical head 5 enters a recording state and emits light so that the laser light intensity (b) continuously becomes constant at _PW. Then, the perpendicular magnetization film 3 of the magneto-optical disk 1 is locally irradiated, and the temperature of the perpendicular magnetization film 3 in the irradiated portion is raised to a value near the Curie point or above the Curie point. Here, when a bias magnetic field is applied, the magnetization of the perpendicular magnetization film of the magneto-optical disk 1 is determined according to the direction and strength of the applied magnetic field.

Here, in the present invention, as shown in (c), a magnetic field “± Ha” stronger than a magnetic field strength “± H” sufficient to determine the magnetization of the perpendicular magnetization film 3 at the front of the recording pit.
Is applied.

When the application direction of the bias magnetic field changes from “−H” to “+ H”, the magnetic field intensity applied to the perpendicular magnetization film 3 momentarily becomes zero, and a magnetic field in the “+” direction is applied.
The magnetic field intensity changes to “+ H”, and the direction of the magnetization of the perpendicular magnetization film 3 is determined. However, as mentioned above,
When the direction of the applied magnetic field is reversed, that is, in the transition region of the applied magnetic field, the direction of the magnetization of the perpendicular magnetization film 3 becomes unstable, and the edge of the recording pit as shown in FIG. Irregularities occur in the parts. Therefore, when a stronger magnetic field strength, that is, a magnetic field “± Ha” equal to or more than “± H” is applied, the magnetization direction of the perpendicular magnetization film 3 changes the temperature distribution of the perpendicular magnetization film 3 by the laser beam irradiation to the pattern and the intensity of the applied magnetic field. Therefore, the direction of magnetization is determined even in a lower temperature distribution region, that is, a wider region than when the direction of magnetization is determined by “± H”.

Therefore, a strong magnetic field strength “± Ha” of “± H” or more is applied including the region where the magnetization direction of the perpendicular magnetization film 3 generated in the transition region where the magnetic field is reversed is unstable. Thus, the direction of magnetization of the perpendicular magnetization film 3 is determined. As a result, good recording pits with no irregularities at the edges of the recording pits are formed. Therefore, when a bias magnetic field is applied with an intensity as shown in (c), a recording pattern as shown in (d) is formed, and a recording pattern with a good recording pit edge is formed. Here, the white portions and the hatched portions indicate that the perpendicular magnetization film 3 is magnetized upward and downward, respectively. Therefore, the reproduced signal in a state where such a recording pattern (d) is formed has a small number of nozzles and a small peak shift and jitter.

It is apparent that the perpendicular magnetization film according to the present invention is applicable not only to a single-layer recording medium but also to a multilayer film.

[Effects of the Invention] As described above, according to the present invention, the intensity of a bias magnetic field to be applied is stronger at the front of a recording pit to be formed than at other regions in the recording pit, and the perpendicular magnetization of the recording medium is increased. By setting the magnetic field strength ± Ha larger than the magnetic field strength ± H sufficient to determine the direction of magnetization of the film, it is possible to eliminate irregularities generated at the edge of the recording pit in the transition region of the magnetic field modulation, thereby reducing noise. In addition, there is an effect that a good reproduced signal with little peak shift and jitter can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the magneto-optical recording apparatus of the present invention, and FIG. 2 is an operation diagram for explaining the operation of the magneto-optical recording method of the present invention. FIG. 3 is a configuration diagram of a conventional magneto-optical recording / reproducing apparatus. FIG. 4 is an operation diagram for explaining the operation of the conventional magneto-optical recording / reproducing apparatus. 1: Magneto-optical disk 2: Glass substrate or plastic substrate 3: Perpendicular magnetization film, 4: Optical head 5: Semiconductor laser, 6: Condensing lens 7: Electromagnet, 8: Coil 9: Magnetic field modulation circuit 10: Bias magnetic field waveform adjustment Circuit 11: protective film

Claims (2)

(57) [Claims] 1. A means for irradiating a condensed light to a magneto-optical recording medium having a perpendicular magnetic film, and a portion of the medium irradiated with the light which is modulated according to a recording signal and magnetizes the perpendicular magnetic film. And a bias applying means for applying a bias magnetic field having a magnetic field strength ± H sufficient to determine the direction of the magnetic field, and recording information by forming recording pits magnetically. At the front of the pit, the intensity of the applied bias magnetic field is stronger than other areas in the recording pit,
And a bias magnetic field waveform adjusting means for setting a magnetic field strength ± Ha larger than the magnetic field strength ± H. 2. A method of irradiating a focused light on a magneto-optical recording medium having a perpendicular magnetic film, modulating a portion of the medium irradiated with the light in accordance with a recording signal, and adjusting a magnetization of the perpendicular magnetic film. In a magneto-optical recording method in which information is recorded by applying a bias magnetic field having a magnetic field strength ± H sufficient to determine the direction and magnetically forming a recording pit, the bias is applied at the front of the recording pit to be formed. The intensity of the bias magnetic field is stronger than other areas in this recording pit,
And a magnetic field intensity ± Ha larger than the magnetic field intensity ± H.