JPH0740381B2 - Optical recording medium - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an optical recording medium of a rewritable optical recording / reproducing apparatus.

2. Description of the Related Art In recent years, optical recording media have come to be used for document files, still image files, etc. as a medium capable of storing information at high density.

Conventionally, in order to achieve a large capacity and high density of a disc type optical recording medium, the tracks for recording information signals are provided in a spiral or concentric shape, and the track spacing is narrowed to increase the recording density. It has been done.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in the method as described above, since the recording area of the information signal and the unrecordable area are not clearly separated, the disc type optical recording medium is recorded at the time of recording the information signal. When the track pitch is narrowed, the recording bit width is unnecessarily widened and crosstalk occurs during reproduction.

In view of the above problems, the present invention provides an optical recording medium capable of significantly reducing crosstalk and achieving high density and large capacity.

In order to achieve this object, the optical recording medium of the present invention has a non-recordable area between a recording track area and an adjacent recording track area.

Further, in the magneto-optical recording medium, the perpendicular magnetization directions of the recording track area and the unrecordable area in the unrecorded state are opposite to each other. Further, in the phase change type optical recording medium, the unrecorded state of the recording track area and the unrecordable area are made different from each other, that is, crystalline and amorphous.

Action The present invention provides the above-described non-recordable area,
It is possible to prevent the recording bit width of the information signal from unnecessarily increasing, and it is possible to significantly reduce crosstalk during reproduction.

Examples Examples of the present invention will be described below with reference to the drawings.

FIG. 1 is a partial sectional view of a magneto-optical disk which is an optical recording medium according to an embodiment of the present invention. In FIG. 1, 1 is a substrate and 2 is a recording film provided on the substrate.

Regarding the optical recording medium in which the magneto-optical recording film 2 is provided on the substrate 1 having the guide groove, when the recording track area (hereinafter referred to as the recording area) is the convex portion of the substrate and the unrecordable area is the concave portion, the recording area The magnetization in the upward direction and the non-recordable area are magnetized in the opposite direction to the recording area before the information signal is recorded. After performing such processing, while applying a downward external magnetic field,
An information signal is recorded by irradiating the recording area with modulated laser light. That is, only the portion irradiated with the laser light and having a certain temperature or higher has the magnetization reversal due to the influence of the external magnetic field, and the recording bit is formed.
However, since the non-recordable area is magnetized in the same direction as the external magnetic field, the magnetization does not reverse even when the temperature rises. Therefore, it is possible to prevent the recording bit width from unnecessarily increasing. In other words, the unrecordable area is
Even if the temperature rises due to the modulated laser light, the state does not change at all. Therefore, during reproduction of the information signal, crosstalk caused by picking up unnecessary signals from other than the target recording track can be significantly reduced.

FIG. 2 is a characteristic diagram showing the crosstalk of the magneto-optical recording medium shown in FIG.

A signal with a single frequency of 500 kHz was recorded under the recording conditions of a medium input laser power of 3 mw and an externally applied magnetic field of 400 oe medium moving speed of 2 m / s. FIG. 2 shows the ratio of the signal level that leaks out when a non-recorded track adjacent to the track is reproduced with respect to the signal detection level when the recorded track is reproduced. The black circles represent the magneto-optical recording media according to the embodiments of the present invention, and the white circles represent the conventional magneto-optical recording media. The recording area and the unrecordable area are not separated.

As can be seen from FIG. 2, the crosstalk was significantly reduced, and an improvement effect of about 8 dB was obtained when the track pitch was 1.6 μm.

In this embodiment, the recording area is a convex portion, but it may be a concave portion. Further, although upward magnetization is applied to the recording area and downward magnetization is applied to the unrecordable area, the magnetizations in the opposite directions may be used. In that case, the external magnetic field used during recording is in the opposite (upward) direction.

Further, in addition to the magneto-optical recording medium, it can be applied to, for example, an optical recording medium that utilizes a phase change, that is, a change between a crystalline state and an amorphous state. That is, the recording area is made crystalline and the unrecordable area is made amorphous. The recording of the information signal is performed by irradiating the recording area with the modulated laser beam. That is, only the portion which is irradiated with the laser beam and has risen above a predetermined temperature changes to an amorphous state, and a recording bit is formed. However, since an amorphous non-recordable area is previously formed between the recording areas, the recording bit width does not increase more than necessary, and crosstalk can be reduced.

Effects of the Invention According to the present invention as described above, the crosstalk of the optical recording medium can be significantly reduced.

In particular, when the track pitch is narrowed and the recording density is increased, crosstalk during reproduction can be significantly reduced and the deterioration of signal quality can be prevented. Therefore, the present invention provides an optical recording medium of high density and large capacity. It is very effective to do this.

[Brief description of drawings]

FIG. 1 is a sectional view of an optical recording medium in an embodiment of the present invention, and FIG. 2 is a characteristic diagram of the same crosstalk. 1 ... Substrate, 2 ... Recording film.

Claims (2)

[Claims] 1. An optical recording medium capable of magneto-optical recording, comprising:
A non-recordable area is provided between a recording track area for recording / reproducing an information signal and a recording track area adjacent to the recording track area, and information about the magnetization direction of the recording track area and the magnetization direction of the non-recordable area is provided. The optical recording medium is characterized in that the recording medium and the recording medium are opposite to each other when not recorded. 2. A phase change type optical recording medium, wherein a non-recordable area is provided between a recording track area for recording / reproducing an information signal and a recording track area adjacent to the recording track area, and the recording track. The optical recording medium is characterized in that the area and the non-recordable area are in a different state of crystalline and non-crystalline when information is not recorded.