JP2003099930A - Method of recording information on optical recording medium, information recording device, and optical recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of recording information on an optical recording medium, which is suitable to realize a high data transfer rate. SOLUTION: This is an information recording method for an optical recording medium, which radiates a laser beam to the recording layer 14 of the recording medium. The information is recorded by setting Pe/Pw to 0.37 or less, representing the recording power of the laser beam by Pw, and the erasing power of the beam by Pe. Thus, in this invention, the recording layer 14 does not accumulate excessive heat, since Pe/Pw is set to 0.37 or less. For the above reason, there is no heat interference between the record marks, and the record marks can be formed in good shape.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for recording information on an optical recording medium, and more specifically,
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information recording method and an information recording device on an optical recording medium suitable for realizing a high data transfer rate. The present invention also relates to an optical recording medium, and more particularly to an optical recording medium capable of recording at a high data transfer rate.

[0002]

2. Description of the Related Art Conventionally, an optical recording medium typified by a CD and a DVD has been widely used as a recording medium for recording digital data. The data recording method is to record data to be recorded on a track. A method of modulating the length of a recording mark along the line is widely used.

When such a recording system is used, a reproducing laser beam is irradiated along a track of an optical recording medium at the time of reading data, and the reflected light is detected to read the information of the recording mark. . Further, when writing data, a recording laser beam is irradiated along the track of the optical recording medium to form a recording mark having a predetermined length. For example, D which is a kind of optical recording medium in which data can be rewritten by the user
In VD-RW, recording marks having a length corresponding to 3T to 11T and 14T (T is one clock cycle) are used, and data is recorded by this.

When recording data on an optical recording medium, a recording laser beam having a pulse width the same as the time corresponding to the length of a recording mark to be formed is generally applied to the optical recording medium. Instead, the optical recording medium is irradiated with a recording laser beam consisting of a number of pulse trains determined based on the type of recording mark to be formed, thereby forming a recording mark having a predetermined length.
For example, in the above-described data recording on the DVD-RW, n-1 or n-2 (n is a kind of recording mark, which is a value of 3 to 11 or 14) pulses are consecutive. Irradiate, which results in 3T ~ 11
Either recording mark having a length corresponding to T and 14T is formed. Therefore, in the case of n-2, it is 1 when a recording mark having a length corresponding to 3T is formed.
When the recording mark having a length corresponding to 11T is formed, 9 pulses are used. Further, in the case of n-1, two pulses are used when forming a recording mark having a length corresponding to 3T, and when forming a recording mark having a length corresponding to 11T. Ten pulses will be used.

[0005]

In recent years, there has been a strong demand for further improvement in the data transfer rate for optical recording media, and in order to realize this, it is effective to increase the linear velocity in recording / reproducing. There is a need to increase the clock frequency.

However, if the clock frequency is increased, the period (T) of one clock is shortened, and the time for forming each recording mark is shortened in proportion to this.
Generally, a recording mark is formed by heating with a recording laser beam and subsequent cooling. Therefore, when the time for forming each recording mark becomes short, it is very difficult to set the heating period and the cooling period appropriately. It will be difficult.

According to the research conducted by the present inventors, when the time for forming each recording mark becomes short, the cooling is particularly insufficient and excessive heat accumulation occurs, causing thermal interference between the recording marks. There was found. When such thermal interference occurs, the shape of the formed recording mark becomes improper and the signal quality (jitter) deteriorates. Problems like this
The higher the data transfer rate, the more remarkable it becomes. The data transfer rate considering the format efficiency is 60 Mb.
It was found that when the data transfer rate was increased to about ps, the deterioration of the jitter due to the thermal interference was observed, and when the data transfer rate was increased to about 90 Mbps, the jitter was significantly deteriorated.

Accordingly, it is an object of the present invention to provide an improved information recording method on an optical recording medium and an improved information recording apparatus.

Another object of the present invention is to provide an information recording method and an information recording apparatus on an optical recording medium suitable for realizing a high data transfer rate.

Another object of the present invention is to provide an optical recording medium capable of recording at a high data transfer rate.

Still another object of the present invention is to provide information to an optical recording medium capable of sufficiently erasing old recording data when a new recording mark is directly overwritten on an already written recording mark. A recording method and an information recording apparatus are provided.

[0012]

The object of the present invention is to:
A method for recording information on an optical recording medium by irradiating a recording layer of the optical recording medium with a laser beam, wherein the recording power of the laser beam is Pw and the erasing power of the laser beam is Pe In addition, it is achieved by a method of recording information on an optical recording medium, characterized in that Pe / Pw is set to 0.37 or less to record the information.

According to the present invention, since Pe / Pw is set to 0.37 or less, excessive heat storage does not occur in the recording layer. Therefore, thermal interference does not occur between recording marks, and it becomes possible to form recording marks having a good shape.

In a preferred embodiment of the invention, P
The information is recorded by setting e / Pw to 0.3 or less.

In a further preferred aspect of the present invention, the information is recorded at a data transfer rate of 60 Mbps or higher.

[0016] In a further preferred aspect of the present invention, the information is recorded at a data transfer rate of 90 Mbps or more.

The above object of the present invention is also an information recording apparatus for recording information by irradiating a recording layer of an optical recording medium with a laser beam, wherein the recording power of the laser beam is Pw, and the laser beam is erased. This is achieved by an information recording apparatus characterized in that, when the power is Pe, Pe / Pw is set to 0.37 or less to record the information.

The above object of the present invention is also an optical recording medium having at least a recording layer for recording information by forming a plurality of recording marks on the recording layer, and having a recording power of a recording laser beam. Where Pw is Pw and the erasing power of the recording laser beam is Pe, the information necessary for recording the information by setting Pe / Pw to 0.37 or less is stored in the recording layer. This is achieved by an optical recording medium characterized by the above.

In a preferred embodiment of the present invention, the information necessary for recording the information with the data transfer rate set to 60 Mbps or more is further stored in the recording layer.

[0020]

DETAILED DESCRIPTION OF THE INVENTION Referring to the accompanying drawings,
A preferred embodiment of the present invention will be described in detail.

FIG. 1 is a diagram schematically showing a main part of an information recording apparatus according to a preferred embodiment of the present invention.

The information recording apparatus according to this embodiment is shown in FIG.
2, a spindle motor 2 for rotating the optical recording medium 1, a head 3 for irradiating the optical recording medium 1 with a recording laser beam, and a controller 4 for controlling the operations of the spindle motor 2 and the head 3. A laser drive circuit 5 for supplying a laser drive signal to the head 3;
And a lens drive circuit 6 for supplying a lens drive signal.

Further, as shown in FIG. 1, the controller 4 includes a focus servo follow-up circuit 7, a tracking servo follow-up circuit 8 and a laser control circuit 9. When the focus servo follow-up circuit 7 is activated, the recording surface of the rotating optical recording medium 1 is focused, and when the tracking servo follow-up circuit 8 is activated, the eccentric signal of the optical recording medium 1 is output. The spot of the laser beam automatically follows the track. The focus servo follow-up circuit 7 and the tracking servo follow-up circuit 8 are respectively provided with an automatic gain control function for automatically adjusting the focus gain and an automatic gain control function for automatically adjusting the tracking gain. The laser control circuit 9 is a circuit that generates a laser drive signal supplied from the laser drive circuit 5, and generates an appropriate laser drive signal based on the recording condition setting information recorded on the optical recording medium 1. I do. Here, the recording condition setting information is various conditions necessary for recording data on the optical recording medium 1, for example, the power of the recording laser beam,
The information used to specify the recording strategy, modulation method, etc., which will be described in detail below. As the recording condition setting information, not only concretely indicate each condition necessary for recording data, but also by specifying any of various conditions stored in advance in the information recording device, the recording condition can be specified. It includes things to do.

The focus servo follow-up circuit 7,
The tracking servo follow-up circuit 8 and the laser control circuit 9 do not need to be circuits incorporated in the controller 4, and may be components separate from the controller 4. Furthermore, these do not have to be physical circuits and may be software executed in the controller 4.

Next, the structure of the optical recording medium according to this embodiment will be described.

FIG. 2 shows an optical recording medium 1 according to this embodiment.
It is sectional drawing which shows the structure of.

As shown in FIG. 2, the optical recording medium 1 comprises:
The substrate 11 having a thickness of about 1.1 mm and the thickness of about 10 to 30
The reflective layer 12 having a thickness of 0 nm and the second layer having a thickness of approximately 10 to 50 nm
Dielectric layer 13 and recording layer 14 having a thickness of about 5 to 30 nm
And a first dielectric layer 15 having a thickness of about 30 to 300 nm.
And a light transmission layer 16 having a thickness of about 50 to 150 μm. In addition, a hole 17 is formed in the central portion of the optical recording medium 1.
Is provided. In recording data on an optical recording medium having such a structure, the distance (working distance) between the objective lens, which is a part of the head 3 and converges the recording laser beam, and the surface of the optical recording medium 1 is The beam spot diameter is set to be extremely narrow (for example, about 80 to 150 μm), and thus a beam spot diameter extremely smaller than that of the conventional one is realized. The optical recording medium 1 having such a structure can realize a large capacity and a high data transfer rate. The above-mentioned recording condition setting information is recorded on the optical recording medium 1.

The recording layer 14 of the optical recording medium 1 is composed of a phase change film, and data is recorded by utilizing the fact that the reflectance in the crystalline state is different from the reflectance in the amorphous state. Be seen. Specifically, the state of the recording layer 14 in the unrecorded area is a crystalline state, and therefore the reflectance thereof is, for example, 20%. When recording some data in such an unrecorded area, according to the data to be recorded, a predetermined portion of the recording layer 14 is heated to a temperature exceeding the melting point and then rapidly cooled to change to an amorphous state. The reflectance in the portion in the amorphous state is, for example, 7%, whereby the predetermined data is recorded. Then, in the case of overwriting the once recorded data, the portion of the recording layer 14 in which the data to be overwritten is recorded is heated to a crystallization temperature or higher to return the portion to the crystalline state, and then the portion According to the data to be recorded,
A predetermined part is changed to an amorphous state.

In this case, the power Pw (recording power) of the recording laser beam emitted when the recording layer 14 is melted
And the power Pb (base power) of the recording laser beam emitted when cooling the recording layer 14 and the power Pb of the recording laser beam emitted when crystallizing the recording layer 14.
The relationship with e (erase power) is Pw>Pe> Pb. Therefore, when recording data on the optical recording medium 1, the controller 4 determines the laser control circuit 9 based on the recording condition setting information read from the optical recording medium 1.
The laser drive circuit 5 is controlled so that the power of the recording laser beam becomes Pw, Pe, or Pb via this, and based on this, the laser drive circuit 5 controls the power of the laser drive signal.

In this embodiment, the relationship between the power Pw of the recording laser beam and Pe is Pe / Pw ≦ 0.3.
Set to 7. As an example, the powers Pw, Pe and Pb of the recording laser beam are 6.5 mW and 2.
It is set to 4 mW and 0.1 mW. In the case of this example, in the optical recording medium 1 according to the present embodiment, the powers Pw, Pe and Pb of the recording laser beam are 6.5 mW, respectively.
The recording condition setting information for instructing setting to 2.4 mW and 0.1 mW is stored, and the information recording apparatus shown in FIG. 1 uses the recording laser beam power as described above based on this. Set.

Recording laser beam powers Pw and Pe
Such a setting is effective when the data transfer rate is high, particularly when the data transfer rate considering the format efficiency is about 60 Mbps or more, and the data transfer rate considering the format efficiency is about 90 Mbps.
In the above case, it is preferable to set Pe / Pw ≦ 0.3. The data transfer rate at which the information recording apparatus shown in FIG. 1 records data is also determined based on the recording condition setting information read from the optical recording medium 1.

In the information recording method according to the present embodiment, the (1,7) RLL modulation method is adopted. That is, the optical recording medium 1 according to the present embodiment has (1,
7) The recording condition setting information for instructing that the RLL modulation method should be adopted is stored. However, it is needless to say that the application of the information recording method according to the present invention is not limited to the case where such a modulation method is used, and is applicable even when another modulation method is used. In this specification, the irradiation method of the recording laser beam for forming the recording mark, that is, the setting of the pulse number of the recording laser beam, the pulse width of each pulse, the pulse interval, the pulse power, etc. Sometimes called "strategy".

FIG. 3 is a diagram showing a recording strategy when a recording mark having a length corresponding to 2T is formed.

As shown in FIG. 3, when forming a recording mark having a length corresponding to 2T, the pulse number of the recording laser beam is set to "1". Here, the pulse number of the recording laser beam is defined by the number of times the power of the recording laser beam is increased to Pw. More specifically, when the timing at which the recording laser beam is located at the start point of the recording mark is time ts and the timing at which the recording laser beam is located at the end point of the recording mark is time te, from time ts to time te. In the meantime, the power of the recording laser beam is once set to Pw and then to the power Pb. Here, the power of the recording laser beam before time ts is set to Pe, and the rise of the recording laser beam is started at time ts. Also,
The power of the recording laser beam at time te is set to Pe or Pb. As described above, in this embodiment, Pe / Pw ≦ 0.37 is set.

During the period of Tpulse, the recording layer 14 of the optical recording medium 1 receives high energy and its temperature exceeds the melting point, and during the period of Tcl, the recording layer 14 of the optical recording medium 1 is rapidly cooled. . As a result, a recording mark having a length corresponding to 2T is formed on the recording layer 14 of the optical recording medium 1. After that, the power of the recording laser beam is set to Pe, but in the present embodiment, the power of Pe is suppressed and Pe / Pw ≦ 0.37 is set, so that excessive heat storage in the recording layer 14 is caused. Does not occur. Therefore, thermal interference does not occur between recording marks, and recording marks having a good shape are formed.

The formation of recording marks having a length corresponding to 3T to 8T is similar to the case of forming recording marks having a length corresponding to 2T, and Pe / Pw≤0.37 is set. As a result, excessive heat storage in the recording layer 14 is prevented.

[0037]

EXAMPLE First, having the structure shown in FIG. 2, the substrate 11 had a thickness of 1.1 mm, and the reflective layer 12 had a thickness of 150 n.
m, the thickness of the second dielectric layer 13 is 40 nm, the thickness of the recording layer 14 is 15 nm, the thickness of the first dielectric layer 15 is 40 nm, and the thickness of the light transmission layer 16 is 100 μm. The optical recording medium 1 was prepared.

For such an optical recording medium 1, (1,
7) Conditions # 1 and # shown in Table 1 according to the RLL modulation method
2, a mixed signal composed of recording marks each having a length corresponding to 2T to 8T was formed.

[0039]

[Table 1] As shown in Table 1, under the conditions # 1 and # 2, Pe / Pw ≦
The value is 0.37, and the condition # 2, which is a data transfer rate of 90 Mbps in consideration of format efficiency, is set to have a smaller value (Pe / Pw ≦ 0.3).

Next, the clock jitter of the mixed signal was measured. In the measurement, the "fluctuation (σ)" of the reproduced signal is obtained by a time interval analyzer, and σ / T
It was calculated by w (Tw: one cycle of clock).

Table 2 shows the measurement results.

[0042]

[Table 2] As shown in Table 2, it can be seen that the jitter shows a relatively low value under both conditions # 1 and # 2.

As comparative examples, the conditions # 3 and # shown in Table 3 were used.
4, a mixed signal composed of recording marks each having a length corresponding to 2T to 8T was formed.

[0044]

[Table 3] As shown in Table 3, the conditions # 3 and # 4 differ from the conditions # 1 and # 2 only in the level of Pe, and the conditions # 3 and # 4 are Pe / Pw> 0.37.

Next, the clock jitter of the mixed signal was measured.

Table 4 shows the measurement results.

[0047]

[Table 4] As shown in Table 4, it can be seen that the jitter under the conditions # 3 and # 4 is worse than the jitter under the conditions # 1 and # 2, respectively.

As described above, in this embodiment, the ratio (Pe / Pw) of the power Pw and Pe of the recording laser beam.
Is set to 0.37 or less, the recording layer 14
There is no excessive heat storage. Therefore, thermal interference does not occur between recording marks, and it becomes possible to form recording marks having a good shape.

The present invention is not limited to the above embodiments, and various modifications can be made within the scope of the invention described in the claims, and these are also included in the scope of the present invention. It goes without saying that it is a thing.

For example, as the optical recording medium according to the above embodiment, the optical recording medium 1 having the structure shown in FIG. 2 is mentioned, but the optical recording medium to which the present invention is applicable has the structure. The medium is not limited, and the present invention can be applied to an optical recording medium having a different structure.

[0051]

As described above, according to the present invention,
An information recording method for an optical recording medium, an information recording apparatus, and an optical recording medium suitable for realizing a high data transfer rate can be provided.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a main part of an information recording apparatus according to a preferred embodiment of the present invention.

FIG. 2 is a sectional view schematically showing the structure of an optical recording medium 1 according to a preferred embodiment of the present invention.

FIG. 3 is a diagram showing a recording strategy when a recording mark having a length corresponding to 2T is formed.

[Explanation of symbols]

1 Optical recording medium 2 spindle motor 3 heads 4 controller 5 Laser drive circuit 6 lens drive circuit 7 Focus servo tracking circuit 8 Tracking servo tracking circuit 9 Laser control circuit 11 board 12 Reflective layer 13 Second dielectric layer 14 Recording layer 15 First Dielectric Layer 16 Light transmission layer 17 holes

Continued front page    F-term (reference) 5D029 JC20 PA01                 5D090 AA01 BB04 CC01 DD05 EE02                       GG33 KK03                 5D119 AA23 AA24 BA01 BB03 DA01                       EC09 HA20 HA50 HA52                 5D789 AA23 AA24 BA01 BB03 DA01                       EC09 HA20 HA50 HA52

Claims (7)

[Claims] 1. A method for recording information on an optical recording medium, wherein information is recorded by irradiating a recording layer of the optical recording medium with a laser beam, wherein a recording power of the laser beam is P.
w, when the erasing power of the laser beam is Pe, the information is recorded on the optical recording medium by setting Pe / Pw to 0.37 or less. 2. The method for recording information on an optical recording medium according to claim 1, wherein Pe / Pw is set to 0.3 or less to record the information. 3. The method for recording information on an optical recording medium according to claim 1, wherein the information is recorded with a data transfer rate set to 60 Mbps or more. 4. The method of recording information on an optical recording medium according to claim 2, wherein the information is recorded with a data transfer rate set to 90 Mbps or more. 5. An information recording apparatus for recording information by irradiating a recording layer of an optical recording medium with a laser beam, wherein the recording power of the laser beam is Pw and the erasing power of the laser beam is Pe. In addition, the information recording apparatus is characterized in that Pe / Pw is set to 0.37 or less to record the information. 6. An optical recording medium having at least a recording layer for recording information by forming a plurality of recording marks on the recording layer, wherein the recording power of a recording laser beam is Pw, Erase power of laser beam is P
The optical recording medium is characterized in that the information necessary for recording the information by setting Pe / Pw to 0.37 or less is stored in the recording layer, where e is e. 7. The optical recording medium according to claim 6, wherein the information necessary for recording the information with the data transfer rate set to 70 Mbps or more is further stored in the recording layer. .