JPH0792938B2 - Magneto-optical recording method - Google Patents

Description

The present invention relates to applying a magnetic field to a magneto-optical recording medium, condensing a light beam, and modulating the intensity of the light beam based on information to be recorded. The present invention relates to a magneto-optical recording method for recording information.

[Conventional technology]

In conventional magneto-optical recording, information is erased and recorded by the following method.

(1) By applying an upward or downward magnetic field perpendicular to the surface of the recording medium and irradiating a light beam having a constant intensity, the magnetization direction of the recording medium is made constant. (Erase) (2) By applying a magnetic field in the opposite direction to that when erasing the recording medium and irradiating a light beam whose intensity is modulated based on the information to be recorded, the direction of the magnetization of the recording medium is accordingly adjusted. Invert. (Recording) In this method, the direction of the magnetic field is opposite during erasing and recording, so recording is performed while erasing, so-called "overwriting".
It has the drawback that it cannot

On the other hand, a pseudo "overwriting" method has been proposed in which two adjacent light beams are irradiated to adjacent tracks on a recording medium, and erasing is performed on one side while recording is performed on the other side. (See Sho 60-93654). The structure of this recording method
This will be described with reference to FIGS. 3 (a) and 3 (b). The light beam 1 and the light beam 2 are recorded on the recording medium 4 by the common objective lens 3.
On the tracks 5 and 6, respectively. The distance between the centers of the tracks 5 and 6 is 2d.

In FIG. 3A, the downward magnetic field H is applied to the recording medium 4.
Is applied to record with the light beam 1 and erase with the light beam 2. At this time, a pit 7 magnetized downward is formed on the track 5 magnetized upward in advance, and the track 6 is magnetized uniformly downward.

On the other hand, in FIG. 3B, an upward magnetic field H is applied to the recording medium 4, recording is performed with the light beam 2 and erasing is performed with the light beam 1. At this time, the upwardly magnetized pits 8 are formed in the track 6 which has been previously magnetized downward, and the track 5 is uniformly magnetized upward.
By repeating the operation of FIGS. 3A and 3B, the state in which the information is always recorded on either the track 5 or the track 6 is maintained. If one type of information is recorded using two tracks in this way, erasing and recording can be performed at the same time, and pseudo "overwriting" can be realized.

[Problems to be solved by the invention]

In the method described above, since one type of information is recorded using two tracks, the recording capacity is larger than that of the normal method of recording one type of information on one track (which cannot be overwritten). It has the drawback of being reduced to 1/2.

An object of the present invention is to provide a magneto-optical recording method which solves the above-mentioned conventional drawbacks and which has a storage capacity increased by 4/3 as compared with the conventional overwrite method without deteriorating crosstalk during reproduction. Especially.

[Means for solving problems]

According to the configuration of the present invention, a magnetic field is applied to a disk-shaped magneto-optical recording medium having concentric circles or spiral grooves, at least two light beams are condensed, and the intensity of one of these light beams is increased. In a magneto-optical recording method in which information is recorded at a position modulated on the basis of information to be recorded and the recorded information at another position is erased by the other light beam, the magneto-optical recording medium has two adjacent grooves. Center distance of 3d
When the groove width is approximately d, the first light beam of the two light beams is centered on the groove portion and the second light beam is orthogonal to the traveling direction of the groove from the center of the inter-groove portion. Irradiate at positions separated by approximately d, and the groove width is approximately 2d.
In this case, the first light beam is applied to the center of the inter-groove portion, and the second light beam is applied to a position separated by approximately d from the center of the inter-groove portion in the direction orthogonal to the traveling direction of the groove. Is characterized by. Here, 2d is the minimum distance between adjacent recording areas necessary for reproduction without being affected by crosstalk during reproduction.

[Action]

In the magneto-optical recording method of the present invention, when the center-to-center distance between two adjacent grooves is 3d, the magneto-optical recording medium has a width of approximately d when it is irradiated with the first light beam when viewed in the radial direction.
Recording area and the width irradiated with the second light beam is approximately d.
The recording area and the intermediate area, which is not irradiated with the light beam and has a width of approximately d, are sequentially repeated. And
Since one of the first and second light beams is used for recording and the other is used for erasing, one of the two recording areas is always in a state where information is recorded and the other is in a state where information is erased. It has become. Therefore, one kind of information is always recorded in the area of 3d in width, which is a combination of two recording areas and one intermediate area, and the normal method of recording one kind of information in the area of 2d in width ( Memory capacity compared to (cannot overwrite)
Pseudo "overwriting" can be realized simply by reducing to 2/3. Further, at this time, the distance between the centers of the two different recording areas in which the information is recorded is at most 2d, which is not smaller than that of the normal method, so that the crosstalk between the two signals during reproduction is It will never be larger than the normal method.

〔Example〕

 Next, the present invention will be described with reference to the drawings.

1 (a) and 1 (b) are perspective views of a recording medium portion for explaining two embodiments of the present invention. In the figure, 1 and 2 are light beams, 3 is an objective lens, 4 is a recording medium, 7 and 8 are pits,
9 and 10 are recording areas, and 11 is an intermediate area. In the recording medium 4 used in this embodiment, the widths of the groove portion and the inter-groove portion are d and 2d, respectively, and the recording area having the width 2d centered on the boundary between the groove portion and the inter-groove portion and the inter-groove portion adjacent thereto are formed. Intermediate regions having a corresponding width d are provided alternately. Light beam 1 and light beam 2
Is the recording area 9 of the recording medium 4 by the common objective lens 3.
And focused on the recording area 10, respectively. Recording area 9,
The recording area 10 corresponds to the inter-groove portion and the groove portion of the recording medium 4, respectively.

In FIG. 1A, a downward magnetic field H is applied to the recording medium 4.
Is applied to record with the light beam 1 and erase with the light beam 2. At this time, downwardly magnetized pits 7 are formed in the recording area 9 that has been previously magnetized upward, and the recording area 10 is evenly magnetized downward.

On the other hand, in FIG. 1B, an upward magnetic field H is applied to the recording medium 4, recording is performed with the light beam 2 and erasing is performed with the light beam 1. At this time, the upwardly magnetized pits 8 are formed in the recording area 10 that is magnetized downward in advance, and the recording area 9 is evenly magnetized upward.
By repeating the operation of FIGS. 1A and 1B, the state in which the information is always recorded in either the recording area 9 or the recording area 10 is maintained. An intermediate area 11 is provided next to the combined area of the recording areas 9 and 10. The intermediate area 11 corresponds to the groove portion of the recording medium 4. This region is previously magnetized upward or downward uniformly and is not irradiated with the light beam. Further, in this embodiment, tracking servo is performed so that the light beam 2 is irradiated to the center of the groove.

2 (a) and 2 (b) are perspective views of a recording medium portion for explaining another embodiment of the present invention. The recording medium used in this example has a groove portion and an inter-groove portion having a width of 2d and d, respectively, and a recording area having a width of 2d around the boundary between the groove portion and the inter-groove portion and a width corresponding to the groove portion adjacent to the recording area. The intermediate regions of d are provided alternately. Further, in the present embodiment, the tracking servo is performed so that the light beam 1 is always applied to the center of the groove portion.

In addition, FIG. 1 (a), (b) and FIG. 2 (a),
In the embodiment of (b), the distance between the centers of the two light beams is d. However, even when the distance between the centers of the two light beams is larger than d, the distance between the centers when viewed in the radial direction of the recording medium is large. If the two light beams are positioned at two positions with a distance of d, they may be slightly displaced in the direction orthogonal to the radial direction.

〔The invention's effect〕

As described above, in the conventional pseudo “overwrite” method, one kind of information is recorded in the area of 4d width (two tracks), and therefore the area of 2d width (one The storage capacity is halved compared to the conventional method of recording one type of information on a track). On the other hand, in the method of the present invention, since one type of information is recorded in the area having a width of 3d,
The storage capacity is reduced to 2/3 compared to the conventional method. Further, in the method of the present invention, the center-to-center distance between two different recording areas in which information is recorded is at most 2d, which is not smaller than that in the conventional method. Crosstalk between them will not be greater than with conventional methods.

[Brief description of drawings]

1 (a) and 1 (b) are perspective views of a recording medium portion for explaining two embodiments of the present invention, and FIGS. 2 (a) and 2 (b) are recording for explaining another embodiment of the present invention. FIG. 3A and FIG. 3B are perspective views of a recording medium for explaining the principle of the conventional pseudo “overwrite” method. 1,2 ... light beam, 3 ... objective lens, 4 ... recording medium, 5,6 ... track, 7,8 ... pit, 9,10 ... recording area, 11 ... intermediate area.

Claims (1)

[Claims] 1. A magnetic field is applied to a disk-shaped magneto-optical recording medium having concentric circular or spiral grooves and at least two light beams are condensed, and the intensity of one of these light beams is recorded. In a magneto-optical recording method in which information is recorded at a position modulated on the basis of information to be recorded and the recorded information at another position is erased by the other light beam, the magneto-optical recording medium is composed of two adjacent grooves. When the center-to-center distance is 3d and the groove width is approximately d, the first light beam of the two light beams is located at the center of the groove portion, and the second light beam is located at the center of the groove portion. When the groove width is about 2d, the first light beam is centered on the groove portion and the second light beam is on the groove side when the groove width is about 2d. Almost d away from the center of the space in the direction orthogonal to the running direction of the groove A magneto-optical recording method, which comprises irradiating different positions.