JPH08273232A - Optical recording method - Google Patents

Abstract

PURPOSE: To provide an overwrite optical recording method high in recording data transfer speed without making a retry whenever erroneous recording is discriminated by verification. CONSTITUTION: Data overwrite-recorded on a overwritable optical recording medium is verified. When a data error is more than a prescribed level, this data is overwrite-recorded again in the same place without erasing the data.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording method for an overwritable optical recording medium.

[0002]

2. Description of the Related Art In recent years, an optical recording / reproducing method satisfying various requirements including high density, large capacity, high access speed, and high recording and reproducing speed, recording apparatus, reproducing apparatus and recording medium used therefor. Is widespread. There are many types of optical recording / reproducing methods using the principles such as hole formation by heat, phase change, and magneto-optical properties. Among these, the method by phase change or magneto-optical method that can be erased after recording information and can record new information over and over again is a method for computer external memory and consumer audio equipment. Has been widely applied to.

Until recently, in the optical recording / reproducing method, it has been impossible to overwrite the new recorded information without erasing the recorded medium. However, only by modulating the intensity of the illuminating light beam according to the binary information to be recorded,
An overwritable optical recording method, an overwritable optical recording medium used therein, and an overwritable recording device used therein have been proposed.

This will be described by taking magneto-optical recording as an example. In addition,
This method has been applied for patents in multiple countries, of which a patent has been registered in the United States (JP 62-175948 = DE3,619,618A1 =
USP 5,239,524). Hereinafter, this invention is referred to as a "basic invention". The overwritable magneto-optical recording medium used in this magneto-optical recording / reproducing method has a perpendicular magnetic anisotropy (perpendicular magnetic layer or layers) as a storage layer.
Is composed of a plurality of magnetic layers. This magnetic layer is made of, for example, amorphous TbFe, TbFeCo, GdFe, GdFeCo, DyFe, DyFeCo, or the like.

The medium used in the basic invention is defined as "a layer basically consisting of a magnetic thin film capable of perpendicular magnetization (hereinafter referred to as a memory layer or an M layer) and a magnetic thin film capable of perpendicular magnetization. And a recording auxiliary layer (hereinafter, referred to as a recording layer or a W layer), both layers being exchange-coupled, and the magnetization direction of the M layer is not changed at room temperature. It is an overwritable multilayer magneto-optical recording medium in which only the magnetization can be directed in a predetermined direction. The W layer has a lower coercive force Hc and a higher Curie point Tc at room temperature than the M layer.

Information is recorded in the M layer (and also in the W layer as the case may be) in a direction having a magnetization in a direction ("A direction") perpendicular to the substrate and in a direction opposite to that ("reverse A direction"). It is recorded by a mark having magnetization. In this medium, the W layer can have its magnetization direction aligned in one direction by a magnetic field means (for example, an initial auxiliary magnetic field Hini.).
Moreover, at that time, the magnetization direction of the M layer is not reversed, and further, the magnetization direction of the W layer once aligned in one direction is not reversed even when receiving the exchange coupling force from the M layer, and vice versa. The magnetization direction of the M layer is not reversed even when the exchange coupling force from the W layer aligned in one direction is received.

In the recording method of the basic invention, only the direction of magnetization of the W layer of the recording medium is aligned in one direction by the magnetic field means before recording. Then, the medium is irradiated with a laser beam pulse-modulated according to the binarized information. The intensity of the laser beam is controlled to a binary value of high level P _H and low level P _L , which corresponds to the high level and low level of the pulse. This low level is higher than the reproduction level P _R that illuminates the medium during reproduction. As is known, it is common, even when not recording, to turn on the laser at a "very low level", for example to access a given recording location on the medium. This very low level also
The level is the same as or close to the reproduction level P _R.

At the temperature reached by the medium when the medium is irradiated with a low-level laser beam, the magnetization direction of the W layer does not change, and the magnetization direction of the M layer is the domain wall between the M layer and the W layer. Is in the state of not existing. This is called a low temperature process, and the temperature range in which this process occurs is called the low temperature process temperature T _L. On the other hand, at a higher temperature reached by the medium when the medium is irradiated with a high-level laser beam, the magnetization direction of the W layer follows the direction of the recording magnetic field, and M
The magnetization direction of the layer is in a state in which no domain wall exists between the M layer and the W layer. This is called high temperature process, the temperature region in which this process occurs as a high temperature process temperature T _H.

After the irradiation of the laser beam, the magnetic field means works so that the magnetization of the W layer, which follows the direction of the recording magnetic field by the high-level irradiation of the laser beam, follows the direction of the magnetic field means again. Therefore, if the direction of magnetization of the magnetic field means and the direction of the recording magnetic field are reversed, the already recorded M layer
New recording can be repeatedly recorded (that is, overwritten). This is the principle of optical modulation overwrite magneto-optical recording.

[0010] To restate the contents described above a little, by forming a recording mark by irradiating a high level laser beam and erasing the recording mark by irradiating a low level laser beam, new information is added to the old information. It can be said that it is overwritten. When actually recording on an optical recording medium, the optical head is moved to a region to be recorded, and the beam is intensity-modulated according to the binarized information and irradiated on the medium.
However, at this time, due to noise generated, environmental temperature, servo performance of the optical head, defective erasure of information recorded before that, recording may not be performed properly, that is, incorrect information may be recorded. is there. Therefore, up to now, erroneous recording has been prevented by performing verification, which is an operation of confirming whether or not the information was properly recorded, by immediately reproducing the recorded information after recording the information.

[0011]

However, in the conventional optical recording, when it is determined by the verification that the recording is erroneous, the data area in which the information is recorded is once erased, and then the recording (retry) is performed again. Therefore, there is a problem that the recording data transfer speed becomes slow. The present invention solves such problems and provides an overwritable optical recording method with a high recording data transfer rate.

[0012]

In order to solve the above problems, the present inventor has found that in overwriting optical recording, when it is determined that the recording is erroneous, the previous recording mark is more than sufficient by the laser beam intensity of the low level P _L. Most of the reason is that the old information is not erased. Therefore, even if the entire data area is not erased, if overwrite recording is performed again, old information is inevitably erased. It came to eggplant.

Therefore, according to the first aspect of the present invention, when verifying the data overwritten on an overwritable optical recording medium, the data is not erased if the data error is above a predetermined level. To provide an optical recording method for an overwritable optical recording medium, characterized in that the data is overwritten again at the same location. Second, the "optical recording medium is composed of two or more layers exchange-coupled to each other. The optical recording method according to claim 1, which is a magneto-optical recording medium including the magnetic layer.

[0014]

The erasing failure in the optical modulation overwrite recording is because old information before the overwrite recording is recorded in a biased manner from the center of the track, or is recorded larger than a predetermined mark width. This is because the light spot at that time is deviated from the center of the track. However, if overwrite recording is repeatedly performed many times, old information before overwriting is eventually erased.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

[0016]

Example A magneto-optical disk having a diameter of 130 mm and capable of overwriting recording by optical modulation is prepared. First, after recording a single frequency signal of 5 MHz on this disk, this signal is reproduced and the peak level of the signal is memorized.

Next, after overwriting recording of a single frequency signal of 2 MHz on the signal of 5 MHz, the signal of 5 MHz is recorded.
Measure the peak level of the signal at z again and calculate the change from the stored value. Repeat this procedure and plot the amount of change. The result is shown in FIG. From Figure 1,
Old information, 5MHz signal, is new information, 2MH
Every time the z signal is overwritten, it can be seen that it is being erased.

[0018]

As described above, according to the present invention,
Since the retry is not performed each time it is determined that the recording is erroneous in the verification, it is possible to provide the overwrite optical recording method in which the recording data transfer speed is high.

[Brief description of drawings]

FIG. 1 is a flowchart illustrating an optical recording method according to the present invention.

FIG. 2 is a graph showing how an old information signal is erased by overwriting a new information signal.

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical display location G11B 20/18 520 9558-5D G11B 20/18 520C 552 9558-5D 552B 572 9558-5D 572D (72) Inventor Masashi Horikawa 3 2-3 Marunouchi, Chiyoda-ku, Tokyo Inside Nikon Corporation

Claims (2)

[Claims] 1. When verifying data recorded by overwriting on an overwritable optical recording medium, if the data error is equal to or higher than a predetermined level, the data is not erased at the same location without being erased. An optical recording method for an overwritable optical recording medium, which is characterized by performing overwrite recording again. 2. The optical recording method according to claim 1, wherein the optical recording medium is a magneto-optical recording medium including two or more magnetic layers exchange-coupled to each other.