JPH0916965A - Optical disk and recording power setting method for same - Google Patents

Abstract

PURPOSE: To perform recording with optimum power even if there is a difference in optimum value of power between a land and a groove. CONSTITUTION: When header information (address) is recorded on a magnetooptic disk 1, areas having specific header information are defined as trial write areas. Thus, the disk 1 is provided with trial write areas 11 and 12 consisting of both tracks of the land 3 and groove 4. A recording and reproducing device performs recording to and reproduction from the areas 11 and 12 to find optimum recording power regarding the land 3 and optimum recording power regarding the groove 4. Linear interpolation is performed on the basis of the found recording power and recording power regarding all positions on the disk 1 is set as to the land 3 and groove 4 respectively. Consequently, recording to both the land 3 and groove 4 can be done with the optimum power.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk such as a magneto-optical disk or a phase change optical disk, and a recording power setting method for the optical disk.

[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. Efforts are being made to develop. Among the wide range of optical recording / reproducing methods, the magneto-optical recording / reproducing method and the phase change recording / reproducing method are the most attractive because of the unique advantage that the recorded information can be rewritten repeatedly. There is. In these methods, information is recorded by irradiating a part of the recording layer on the medium with a laser beam whose diameter is reduced to about 1 μm to raise the temperature of the recording layer.

In a medium for recording using heat, which is called heat mode recording, it is necessary to appropriately set the power of the laser beam applied during recording. That is, in the above recording / reproducing method, information is expressed by the presence or absence of marks and their length. However, if the laser power during recording is too high, the mark length becomes longer than the desired length. If the power is too low, the mark length will be shortened.

On the other hand, new methods are being studied for further increasing the capacity of optical discs, for example, the adoption of a laser beam having a short wavelength and the method of narrowing the track pitch are being studied. Land / groove recording is a technique that has recently been drawing attention as a means of increasing the capacity. Conventional optical disc recording is performed on only one of the land portion that is a convex portion or the groove portion (guide groove) that is a concave portion, but in the land / groove recording, both the land portion and the groove portion are used as recording tracks. This is a method of improving the recording density by using it.

The land / groove recording medium is manufactured by forming a recording layer on a substrate formed so that the widths of the land portion and the groove portion are substantially the same. Therefore, since the film is formed on the land and the groove of the substrate at the same time, it is considered that there is almost no difference in the characteristics of the recording layer. Therefore, the power of the laser beam at the time of recording has a common value for the land and the groove. Was set to.

[0006]

As described above, in the land / groove recording using the conventional optical disk, both these tracks are recorded with the power common to the land and the groove. However, there is a problem in that the optimum power value may differ between adjacent lands and grooves. As a result, there is a problem in that even if recording and reproducing can be accurately performed on one track of the land or groove, an error occurs on the other track. The present invention has been made to solve the above problems, and provides an optical disk and a recording power setting method for an optical disk that can perform recording with an appropriate power even if the optimum power values for lands and grooves differ. The purpose is to do.

[0007]

The optical disk of the present invention comprises:
As described in claim 1, a trial writing area for obtaining an appropriate laser power at the time of recording is provided in both the land and the groove. Further, as described in claim 2, the trial writing areas are provided at a plurality of positions on the disc.

Further, according to the recording power setting method of the present invention, as described in claim 3, recording / reproducing is performed in the trial writing area provided on the land to obtain an appropriate laser power at the time of recording, and this is set. The recording power for the land is set, the recording / reproducing is performed in the trial writing area provided in the groove to obtain an appropriate laser power at the time of recording, and this is set as the recording power for the groove. Further, as described in claim 4, recording / reproducing is performed in each trial writing area provided in the lands at a plurality of positions to obtain appropriate laser powers at the time of recording, and the lands related to these lands are related. The recording power is set for all positions on the disc, and recording / reproducing is performed in each test writing area provided in the groove at a plurality of positions to obtain an appropriate laser power at the time of recording,
The recording power for the groove is set for all positions on the disk based on these powers.

[0009]

According to the optical disk of the present invention, as described in claim 1, since the trial writing area is provided in both the land and the groove, the trial writing is performed in each of these areas to set an appropriate recording power. It can be carried out. Further, since the test writing areas are provided at a plurality of positions on the disc as described in claim 2, it is possible to set an appropriate recording power according to each position.

Further, according to the recording power setting method of the present invention, as described in claim 3, it is necessary to perform recording / reproducing in the trial writing area to obtain an appropriate laser power at the time of recording for each of the land and the groove. To do. Further, as described in claim 4, recording / reproducing is performed on the trial writing areas at a plurality of positions to obtain appropriate laser powers at the time of recording, and the recording powers at all positions on the disk are determined based on these powers. Is performed for each of the land and the groove.

[0011]

1 (a) is an external view of a magneto-optical disk showing one embodiment of the present invention, and FIG. 1 (b) is a perspective view of a portion B of the magneto-optical disk cut along the line AA. FIG. 1C is an enlarged view showing the state of the trial writing area provided on the magneto-optical disk. In FIGS. 1A and 1B,
1 is a magneto-optical disk, 2 is a substrate with a guide groove having a land portion 3 which is a convex portion and a groove portion 4 which is a concave portion when viewed from the side (upper side in FIG. 1) opposite to the incidence of laser light, 5 is a substrate 2 is an underlayer made of SiN, 6 is a recording layer made of TbFeCo formed on the underlayer 5, 11 is a trial writing area provided at a position of a radius of 30 mm from the center, and 12 is a position of a radius of 60 mm. It is a trial writing area provided in.

In FIG. 1C, 4n is a groove portion,
3n is a land portion adjacent to the inner peripheral side of the groove portion 4n. Similarly, the groove 4 is formed on the inner peripheral side of the land 3n.
n + 1, 4n + 2 and land portions 3n + 1, 3n + 2 are arranged. Next, a method of manufacturing such a magneto-optical disk 1 will be described. First, injection molding or the like is performed using a stamper manufactured by a known master disk manufacturing technique to manufacture a substrate 2 with a guide groove having a diameter of 130 mm.

Subsequently, on the guide grooved substrate 2, an underlayer 5 made of SiN having a thickness of 70 nm, a recording layer 6 made of TbFeCo having a thickness of 50 nm, and a thickness of 70 n not shown.
m by sequentially forming a protective layer made of SiN,
The manufacture of the magneto-optical disk 1 having a recording / reproducing area at a radius of 28 to 61 mm is completed.

In this magneto-optical disc 1, each track of the land portion 3 and the groove portion 4 is divided into units called sectors, and header information including position information on the disc is recorded in each sector. As a method of recording header information, a geometrical unevenness indicating the header information is formed on the substrate 2 with the guide groove in the manufacturing process (preformat).
Then, there is a method (soft format) of writing the header information to the recording layer 6 after the disc 1 is manufactured.

In this embodiment, when the header information is recorded by any of these methods, an area consisting of several tracks and several sectors having specific header information is defined as a trial writing area. Next, such a magneto-optical disk 1
Laser beam wavelength 780 nm, substrate rotation speed 24
The recording / reproducing apparatus (not shown) at 00 rpm is set.

Header information (address) of an area defined as a trial writing area is registered in advance in this recording / reproducing apparatus, and the trial writing area can be accessed based on the registered header information. Has become. Then, the recording / reproducing apparatus carries out trial writing in this area, so that each of the land portion 3 and the groove portion 4 (accurately, the land portion 3 and the recording layer 6 on the groove portion 4) of the magneto-optical disk 1 is Find the optimum recording power. In addition,
The power described below is the power of the laser beam with which the disk 1 is irradiated.

First, the recording / reproducing apparatus uses magneto-optical recording in which the direction of the magnetization of the recording layer 6 is reversed by applying a laser beam and an external magnetic field to the test writing area of the magneto-optical disk 1 with a frequency f0 and a duty of 50. %, And the recording signal as shown in FIG. As a result, the mark as shown in FIG. 2B is recorded on the recording layer 6 of the disc 1.

Next, the recording / reproducing apparatus irradiates the laser beam to the mark in the trial writing area thus recorded, detects the signal as shown in FIG. 2 (c) with the optical head, and binarizes this signal. A reproduction signal such as 2 (d) is obtained. Then, by passing this reproduction signal through a filter, as shown in FIG.
The DC component as shown in (e) is taken out, and this DC component is 0
It is checked whether or not it is within the range of the reference level Vh centered at.

When the DC component is smaller than the reference level Vh, the recording power is increased to perform the same recording / reproduction as described above, and when the DC component is larger than the reference level Vh, the recording power is decreased to perform the recording / reproduction. In this way, writing to the trial writing area is performed while changing the recording power until the DC component falls within the range of the reference level Vh.

The reason why such recording / reproduction is repeated is as follows. As for the optimum recording power, the time widths t1 and t2 in FIG. 2D are equal (duty 50%).
It is the recording power, and the DC component of the reproduced signal is zero at this time. Now, in the groove part 4n + 1 in the trial writing area,
It is assumed that the mark 14 as shown in FIG. 1C is written with the optimum recording power and the mark 13 is written with a power lower than the optimum recording power in the land portion 3n + 1.

When the recording power is low, the length of the mark 13 becomes shorter than the desired length (the length of the mark 14), and as a result, the time width t1 becomes shorter and t2 becomes longer. As a result, the DC component of the reproduced signal becomes smaller than zero. Therefore, when the DC component is smaller than the reference level Vh in a predetermined range centered on 0, the recording power may be increased.

On the contrary, when the recording power is high, the mark length becomes longer than the desired length, and as a result, the time width t1 becomes longer and t2 becomes shorter. As a result, the DC component of the reproduced signal becomes greater than zero. Therefore, when the DC component is larger than the reference level Vh, the recording power may be reduced.
As described above, if the DC component of the reproduced signal is set within the range of the reference level Vh, the power at that time becomes the optimum recording power.

In order to obtain the optimum recording power, the time widths t1 and t2 may be directly measured to obtain the powers so that they are equal. Alternatively, the reproduced signal may be subjected to frequency spectrum analysis to obtain the fundamental frequency f0. Alternatively, the power that minimizes the second harmonic of the frequency 2f0 may be obtained.

The above-described measurement is carried out for each of the land portion 3 and the groove portion 4 in the trial writing area, and the optimum recording power of these is obtained. Table 1 shows magneto-optical disk 1
3 shows the optimum recording power measured in the trial writing areas 11 and 12.

[0025]

[Table 1]

Since the film is formed on the land portion 3 and the groove portion 4 at the same time, there has been almost no difference in the characteristics of the recording layer 6, and it has been conventionally considered that the power for recording or the like may be common. However, as is clear from the above measurement results, there is a difference in optimum power between the land portion 3 and the groove portion 4 which are adjacent to each other.

The following are possible causes for this. For example, although the recording layer 6 is formed on the substrate 2 by sputtering, the composition of the recording layer 6 at the end of the groove portion 4 is slightly different from that of the land portion 3 because the end of the groove portion 4 is behind the land portion 3. This difference in composition is considered to be the cause of the difference in characteristics of the land portion 3 and the groove portion 4. Further, even if there is a micro level difference in the surface state on the recording surface side (upper side in FIG. 1) of the substrate 2, this may cause a difference in the characteristics of the land portion 3 and the groove portion 4.

In this way, for each of the trial writing areas 11 and 12, the value of the recording power for the land portion and the value of the recording power for the groove portion are obtained, and the intensity of the laser irradiated during recording is set. At this time, the recording power obtained from the trial writing area 11 and the trial writing area 1
Based on the recording power obtained from 2, the linear interpolation as in the following equation is performed to obtain the recording power Pw (r) at the position of the radius r.

Pw (r) = [{Pw (r2) −Pw (r1)} / (r2-r1)] × (r−r1) + Pw (r1) (1) In the formula (1), r1 Is the position of area 11 (radius 30
mm), r2 is the position of area 12 (radius 60 mm), P
w (r1) is the recording power obtained in area 11, Pw
(R2) is the recording power obtained in the area 12.

This linear interpolation is applied to the land portion 3 and the groove portion 4.
By performing each of the
The recording power for all the above positions can be set for each of the land portion 3 and the groove portion 4, and recording can be performed with appropriate power for both the land portion 3 and the groove portion 4.

In order to confirm the effect of the present embodiment as described above, data is recorded on the land portion 3 of the magneto-optical disk 1 by the recording / reproducing apparatus, and then the recorded mark is read to reproduce the data. All sectors could be read out accurately. Further, even if data was recorded in the groove portion 4, it was possible to read it out similarly.

On the other hand, a magneto-optical disk having a structure similar to that of the disk 1 and provided with a trial writing area only in the land portion is prepared. Then, when the data is recorded and reproduced in the groove portion having no information about the power (that is,
The recording power obtained from the trial writing area of the land portion is used for recording in the groove portion), and accurate recording / reproduction could not be performed.

In this embodiment, the test writing areas are provided at two points, the inner circumference and the outer circumference, which are located at different radial positions. However, they may be provided at the three points of the inner circumference, the middle circumference, and the outer circumference. It may be more than a point. Further, although the magneto-optical disk has been described in this embodiment, the present invention can be applied to other magneto-optical disks such as a phase change optical disk.

[0034]

According to the present invention, since the trial writing areas are provided in both the land and the groove, the trial writing can be performed in these areas and the recording power can be set respectively. It is possible to record with various powers and prevent erroneous recording and reproduction due to different sensitivities of land and groove.

By providing trial writing areas at a plurality of positions on the disc, recording can be performed with an appropriate power according to each position, and the optical disc can be used as a more reliable optical disc.

Further, by performing recording / reproducing in the trial writing area and obtaining an appropriate laser power at the time of recording for each of the land and the groove, it is possible to perform recording with the appropriate power for both the land and the groove.

Further, recording / reproducing is performed in a plurality of test writing areas to obtain appropriate laser powers at the time of recording, and the recording powers at all positions on the disk are obtained based on these powers. By performing each groove, recording can be performed with an appropriate power according to each position on the disc, and more reliable recording and reproducing can be realized.

[Brief description of the drawings]

FIG. 1 is an external view of a magneto-optical disk according to an embodiment of the present invention, an enlarged view of a portion of the magneto-optical disk seen obliquely from above, and a diagram showing a state of a trial writing area provided on the magneto-optical disk. is there.

FIG. 2 is a recording signal waveform for measuring the optimum recording power,
FIG. 3 is a diagram showing a mark recorded on a magneto-optical disk by this signal, a reproduction signal waveform obtained by reproducing the mark, and a DC component of the reproduction signal.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Magneto-optical disk, 2 ... Substrate with a guide groove, 3 ... Land part, 4 ... Groove part, 5 ... Underlayer, 6 ... Recording layer, 11,
12 ... Trial writing area, 3n to 3n + 2 ... Land portion in the trial writing area, 4n to 4n + 2 ... Groove portion in the trial writing area.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location G11B 11/10 586 9296-5D G11B 11/10 586B

Claims (4)

[Claims] 1. An optical disc using both a land and a groove as recording / reproducing tracks, using a substrate with a guide groove having a land that is a convex portion and a groove that is a guide groove. An optical disc characterized in that a trial writing area for obtaining an appropriate laser power is provided on both the land and the groove. 2. The optical disk according to claim 1, wherein the optical disk is provided with the test writing areas at a plurality of positions on the disk. 3. An optical disk having a trial writing area provided on both a land which is a convex portion and a groove which is a concave portion and which uses both the land and the groove as recording / reproducing tracks, has an appropriate laser power at the time of recording. A method for setting a recording power of an optical disk for setting, wherein recording / reproducing is performed in the trial writing area provided on a land to obtain an appropriate laser power at the time of recording, and this is set as a recording power for the land, A recording power setting method for an optical disk, characterized in that recording / reproducing is performed in the trial writing area provided in the groove to obtain an appropriate laser power at the time of recording, and this is set as the recording power for the groove. 4. An optical disc having a trial writing area provided on a land and a groove at a plurality of positions on the disc, respectively, and having both the land and the groove as recording / reproducing tracks, an appropriate laser power at the time of recording is set. A method for setting the recording power of the optical disk for performing the recording / reproducing in each trial writing area provided on the lands at the plurality of positions to obtain an appropriate laser power at the time of recording, and based on these powers. The recording power for the land is set for all positions on the disc, and recording / reproducing is performed in each test writing area provided in the groove at the plurality of positions to obtain an appropriate laser power at the time of recording. The optical power is characterized in that the recording power for the groove is set for all positions on the disc based on Recording power setting method of click.