JP2002329319A - Optical disk device and recording power control method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical disk device which can set a constant to be multiplied by a minimum recording power to an optimum value in accordance with a condition for recording like the convergence state of a light beam at the time of setting an optimum recording power. SOLUTION: The value of the constant which should be multiplied by the minimum recording power at the time of setting the optimum recording power is set by a constant setting means 22 in accordance with the convergence state of the light beam detected from the minimum recording power (Pmin) and/or the linear speed of an optical disk 1 detected by a linear speed detection means 23 and/or the ambient temperature of the optical disk 1 detected by a temperature detection means 24.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an optical disc apparatus for recording and reproducing information on and from an optical disc, and a recording power control method therefor.

[0002]

2. Description of the Related Art In recent years, optical disks have been put into practical use as mainstream information recording media for large-capacity information such as multimedia data. Abbreviated) have been published one after another.

[0003] As a major approach to the high density, a shorter mark length of a recording mark, a narrower track pitch, and the like are performed. However, as the recording density increases, the influence on the signal quality such as the S / N ratio increases when the light beam condensing state changes due to defocus or disc tilt during recording or reproduction. For this reason, at the time of recording, it is desirable to perform recording with a laser power corrected for an equivalent decrease in the laser power due to a change in the focusing state.

In order to solve such a problem, a minimum recording power for forming a recording mark of a reproduction limit on an optical disk (hereinafter, abbreviated as a minimum recording power or Pmin).
A method has been proposed in which a power obtained by multiplying Pmin by a constant is set as an optimum recording power to a laser power used for data recording (for example, Japanese Patent Application Laid-Open No. HEI 3-2)
No. 32141).

Hereinafter, an example of the above-described conventional optical disk device will be described with reference to the drawings.

FIG. 12 is a block diagram of a conventional optical disk device. In FIG. 12, reference numeral 1 denotes an optical disk, 2 denotes a spindle motor for rotating the optical disk, and 3 denotes an optical head for condensing laser light on the optical disk 1 and detecting recorded information by reflected light from the optical disk 1. Reference numeral 4 denotes a laser power control unit for setting a laser power based on information from a control unit 9 described later, and reference numeral 5 denotes a magnetic head for recording a signal. Reference numeral 6 denotes a band-pass filter, and reference numeral 7 denotes a detector for detecting the intensity of the reproduced signal. Reference numeral 8 denotes a minimum recording power detection unit for detecting Pmin, and 9 denotes a control unit that controls the spindle motor 2, the optical head 3, the laser power control unit 4, and the magnetic head 5, and sets an optimum recording power.

Next, the operation of the optical disk apparatus configured as described above will be described.

When setting the laser power used for data recording, first, the laser power control means 4 sets the power based on information from the control unit 9. The control unit 9
The optical head 3 and the magnetic head 5 are controlled to record a signal of a single frequency on the optical disc 1. Next, this signal is reproduced by the optical head 3 and band-limited by a band-pass filter 6 having the same pass band as the recorded frequency.
The signal intensity of this output signal is detected by the detector 7 and input to the minimum recording power detecting means 8 as the signal intensity.

By repeating this operation while changing the set value of the recording power, the recording power dependency as shown in FIG. 13 can be obtained. The minimum recording power detection means 8 calculates P
min is detected. The detected Pmin is input to the control unit 9, and the control unit 9 sets the power obtained by multiplying the Pmin by a constant as the optimum recording power and sets the laser power used for data recording.

FIG. 14A shows an example of the recording power dependence of the reproduction signal intensity when recording is performed with the light beam condensing state changed. In the figure, a characteristic G represents the recording of the reproduction signal intensity obtained when the recording is performed in a state where the light beam is well focused, and a characteristic B represents the recording of the reproduced signal intensity obtained when the recording is performed in a state where the light beam is not well focused. It is an example of power dependency.
As shown in the figure, the recording power required to obtain the same reproduction signal intensity, for example, a predetermined level of reproduction signal intensity, differs greatly depending on the light beam condensing state.

Therefore, by detecting the minimum recording power in each state and normalizing the minimum recording power (PminG and PminB), it is possible to obtain the normalized recording power dependency as shown in FIG. . That is, irrespective of the light condensing state, by recording with the recording power normalized by Pmin (hereinafter abbreviated as normalized recording power), it is possible to obtain a substantially constant reproduction signal intensity.

Therefore, by recording at a power (α · Pmin) obtained by multiplying the minimum recording power by a constant value (α),
Even when the light beam condensing state changes, the recorded signal intensity can be kept constant.

Note that the value of α may be any value that can provide a signal strength equal to or higher than a predetermined level.

[0014]

However, the above configuration has a problem that an optimum recording power cannot always be set in a high-density disk having a narrow track pitch.

As the density of an optical disk increases and the track pitch becomes narrower, the risk of a phenomenon of deteriorating data of an adjacent track during recording (hereinafter, this phenomenon is referred to as a cross write) increases. This is because the cross light is generated due to the propagation of heat (thermal diffusion) to the adjacent track, and as the track pitch becomes narrower, the adjacent track is more likely to affect the adjacent track.

FIG. 15 shows an example of a change in the amount of cross light depending on the track pitch. The cross light amount in the figure is
It is expressed by the amount of decrease in signal strength of an adjacent track due to recording on a desired track. In the figure, a characteristic W is an example of the recording power dependency of the cross write amount obtained when the track pitch is wide, and a characteristic N is an example when the track pitch is narrow. The minimum recording power at which the cross write occurs (hereinafter, abbreviated as cross write start power or Pcw) becomes lower as the track pitch becomes narrower (PcwN <PcwW).

When a cross write occurs, data on an adjacent track is deteriorated, and in the worst case, a problem occurs that data in a deteriorated portion is lost or cannot be reproduced. Therefore, in a high-density disk, it is necessary to set a recording power in consideration of not only a signal at a predetermined level or more on a desired track but also a cross write.

As described above, since the cross write is generated due to the propagation of heat to the adjacent track (thermal diffusion), the influence of the change in the light beam condensing state on the recording power dependency is described. Is different from the reproduced signal strength shown in FIG. For example, when the light condensing state changes as in FIG. 14A, the recording power dependency of the cross write amount is as shown in FIG.
(A). Here, normalization with the minimum recording power (PminG and PminB) in each state provides a normalized recording power dependency as shown in FIG. 16B, and as the light beam condensing state worsens, the lower the standard, the lower the standard. Cross-write occurs at the modified recording power.

In general, in order to perform highly reliable recording, it is desirable to perform recording using a high laser power within a range where no cross write occurs. Thus, for example,
ΑG · PminG when the light beam is well focused
Is set to the laser power used for data recording, and if the focusing state is poor, αB · PminB is similarly set, so that highly reliable recording can be performed even on a high-density disc, and the adjacent track can be recorded at the time of recording. The danger of cross writing that degrades data can be greatly reduced.

Pmin also changes depending on recording conditions such as the temperature and linear velocity of the optical disk. Also at this time, by setting the laser power used for data recording by using an appropriate value for the constant to be multiplied by Pmin according to each recording condition, cross writing can be prevented and highly reliable recording can be performed.

The present invention has been made in view of the above problems, and sets a constant to be multiplied by a minimum recording power when setting a laser power (optimum recording power) used for recording data in a recording condition such as a light beam condensing state. It is an object of the present invention to provide an optical disk device and a recording power control method for the optical disk device, which can be set to an optimum value according to the condition.

[0022]

In order to achieve the above object, an optical disk apparatus of the present invention is an optical disk apparatus for recording and reproducing data by irradiating an optical disk with a light beam. Recording means for recording, laser power control means for controlling the power of the light beam irradiating the optical disk for the recording means,
Reproducing means for reproducing information recorded on the optical disc; detecting a minimum recording power for forming a record mark of a reproducible limit on the optical disc; and setting a power obtained by multiplying the minimum recording power by a constant as an optimum recording power. It is characterized by comprising an optimum recording power setting means for setting and a constant setting means for setting the value of the constant.

In the optical disk device, it is preferable that the constant setting means sets the value of the constant according to the temperature of the optical disk.

In the optical disk device, it is preferable that the constant setting means sets the value of the constant according to a linear velocity of the optical disk.

In the optical disk device, it is preferable that the constant setting means sets the value of the constant according to a state of focusing of the light beam. Also, in this case,
The condensing state of the light beam can be determined from the minimum recording power for forming the recording mark of the reproduction limit.

When the optical disk device is an optical disk device for recording data by intermittently irradiating a light beam, the constant setting means sets the value of the constant according to the intermittent rate of the light beam. Is preferred.

In the optical disc apparatus, the optical disc apparatus further comprises a correlation detecting means for detecting a correlation between a recording pattern to be recorded on the optical disc by the recording means and a reproduced signal obtained when the recording pattern is reproduced by the reproducing means. Furthermore, the optimum recording power setting means compares the output of the correlation detecting means obtained when the laser power is stepwise changed by the laser power control means with a predetermined level, and the magnitude relation has been changed. It is preferable to detect the recording power at that time as the minimum recording power.

In order to achieve the above object, a recording power control method for an optical disk device according to the present invention is directed to a recording power control method for an optical disk device for recording data by irradiating an optical disk with a light beam. A minimum recording power for forming a recording mark of a possible limit is detected, a power obtained by multiplying the minimum recording power by a constant is set as the optimum recording power, and the value of the constant is changed according to a recording condition. It is characterized by the following.

In the recording power control method for an optical disk device, the value of the constant is set according to at least one of a temperature of the optical disk, a linear velocity of the optical disk, and a condensing state of the light beam. Is preferred.

Further, in the recording power control method for an optical disk device, the focusing state of the light beam can be obtained from a minimum recording power for forming a recording mark of a reproduction limit on the optical disk.

According to the above configuration and method, when setting the laser power (optimum recording power) used for data recording, a constant to be multiplied by the minimum recording power is set according to recording conditions such as the light beam condensing state. Accordingly, it is possible to set an optimal value.

Further, even when the light beam is intermittently irradiated during recording, it is possible to set a constant for multiplying the minimum recording power to an optimum value according to the intermittent rate.

Further, by using the correlation detection for detecting the minimum recording power, even when the minimum recording power is to be performed in the data recording area, it is not necessary to previously erase the data previously recorded in the data recording area. Recording power can be detected with high accuracy and in a short time.

[0034]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS.

(First Embodiment) FIG. 1 is a block diagram showing the configuration of an optical disk device according to a first embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes an optical disk, 2 denotes a spindle motor for rotating the optical disk 1, and 3 denotes an optical head (reproducing) for condensing a laser beam on the optical disk 1 and detecting recorded information by reflected light from the optical disk 1. Means). Reference numeral 4 denotes a laser power control unit for setting a laser power based on information from a control unit 21 described later, and reference numeral 5 denotes a magnetic head for recording a signal. Reference numeral 6 denotes a band-pass filter, and reference numeral 7 denotes a detector for detecting the intensity of the reproduced signal. 8
Is a minimum recording power detecting means for detecting a minimum recording power (Pmin) for forming a recording mark of the reproduction limit on the optical disk 1. A control unit 21 controls the spindle motor 2, the optical head 3, the laser power control unit 4, and the magnetic head 5, and sets an optimum recording power. 22 is a constant setting means for setting a constant value by which the minimum recording power is multiplied when setting the optimum recording power, 23 is a linear velocity detecting means for detecting a linear velocity of the optical disk 1, and 24 is a peripheral temperature of the optical disk 1 Temperature detecting means.

The recording means is constituted by the optical head 3 and the magnetic head 5 described above. Also, the optical disk 1
Is a phase change type optical disk or the like, a recording means is constituted only by the optical head 3.

The above-mentioned minimum recording power detecting means 8
The optimum recording power setting means 25
Is configured.

FIG. 2 shows a first embodiment of the present invention,
1 shows a configuration diagram of an optical disc 1 according to an embodiment (to be described later) and a third embodiment (to be described later).

In FIG. 2, 31 is a substrate, 32 is a recording film, 33 is a data recording area for recording data, and 34 is a track. In FIG. 2, the track 34 is concentric, but is not limited to this, and may be formed in a spiral shape.

Next, the operation of the optical disk device of the first embodiment configured as described above will be described.

The optical head 3 irradiates the optical disk 1 with a light beam, detects the reflected light, and converts it into an electric signal.
This detection signal is supplied to the band pass filter 6, and a focus control unit and a tracking control unit (not shown).

When setting the laser power (optimum recording power) used for data recording, the laser power control means 4
Sets the laser power based on information from the control unit 21. The control unit 21 controls the optical head 3 and the magnetic head 5 to record a signal of a single frequency on the optical disc 1. Next, based on the information from the control unit 21, this signal is reproduced by the optical head 3, and the band is limited by the band pass filter 6 having the same pass band as the recorded frequency. Then, the signal strength of the band-limited signal is detected by the detector 7 and input to the minimum recording power detecting means 8 as the signal strength.

By repeating this operation while changing the set value of the recording power, it is possible to obtain the dependence of the reproduction signal intensity on the recording power as shown in FIG. The minimum recording power detection means 8 detects Pmin by approximation calculation from the recording power dependence of the reproduction signal intensity. Pm
The detection result of “in” is input to the control unit 21 and the constant setting unit 22.

The linear velocity detecting means 23 detects the linear velocity of the optical disk 1, and the detection result is inputted to the constant setting means 22. Further, the temperature detecting means 24 detects the peripheral temperature of the optical disc 1, and the detection result is similarly input to the constant setting means 22.

As means for detecting the linear velocity of the optical disk 1, for example, control information of the spindle motor 2 can be used. As means for detecting the ambient temperature of the optical disk 1, for example, a thermistor can be used.

The constant setting means 22 sets a constant to be multiplied by Pmin when setting the optimum recording power in accordance with the linear velocity of the optical disk 1 and / or the ambient temperature of the optical disk 1 and / or the light beam condensing state. The value is set, and the set value (α ′) is input to the control unit 21. Although the details will be described later, the condensing state of the light beam here is obtained from Pmin in the constant setting unit 22.

Conventionally, the constant multiplied by Pmin when setting the laser power (optimum recording power) used for recording data has been a constant value (α). It is a great feature of the present invention that the variable value (α ′) according to the condition is set.

Next, the operation of the constant setting means 22 and the method of setting the constant (α ') by which the minimum recording power is multiplied will be described.
This will be described with reference to FIGS.

FIGS. 4 (a) and 4 (b) show examples of flowcharts showing the recording power control method of the present invention. Specifically, the constant (α ′) to be multiplied by the minimum recording power is shown. The setting method is shown.

FIG. 4A is a first example of a flowchart showing the recording power control method of the present invention. In the first example, first, in step 1 (S1), the constant setting means 22 sets the optimum constant (α
t) is set.

In general, when data is recorded on the optical disk 1, a desired track on the optical disk 1 is irradiated with a light beam to raise the temperature of the recording film 32 in the optical disk 1 to a predetermined temperature.
For example, in the case of the magneto-optical recording method, data recording is performed by raising the temperature above the Curie temperature. Here, assuming that the temperature of the optical disk 1 when no light beam is irradiated is Tr, the Curie temperature of the recording film 32 is Tc, and the laser power required to raise the temperature of the recording film 32 by a unit temperature is k,
Recording is started when the temperature of the optical disk 1 reaches Tc, and can be expressed as follows.

K = Pmin / (Tc-Tr) (1) Here, it is assumed that the temperature of the optical disk 1 and the temperature of the recording film 32 in the optical disk 1 are substantially equal.

If the optimum recording power is Pwt and the temperature of the optical disc 1 when the light beam is irradiated with this laser power is Twt, k can be expressed as follows.

K = Pwt / (Twt-Tr) (2) Here, from equations (1) and (2), k = Pmin / (Tc-Tr) = Pwt / (Twt-T
r), from which Pwt / Pmin = (Twt-Tr) / (Tc-Tr) (3)

In the equation (3), Twt and Tc are values specific to the disk.
wt is about 240 to 450 ° C, and Tc is about 160 to 300 ° C. Thus, for example, Twt is 380 ° C. and Tc is 2
For a disc at 60 ° C., from equation (3), Pw depends on the temperature (Tr) of the optical disc 1 when no light beam is irradiated.
The value of t / Pmin changes as shown in FIG.

Here, Pwt / Pmin is the ratio between the minimum recording power and the optimum recording power, and the temperature of the optical disc 1 multiplied by the minimum recording power when setting the laser power (optimum recording power) used for data recording. It is nothing but the optimal constant according to. That is, when a certain constant (1.5 in FIG. 5A) is set as a constant value (α) and the laser power used for data recording is set, the optical disc 1 is set at a predetermined temperature (FIG. 5A) corresponding to the certain constant. In the case of a temperature other than (a) the temperature indicated by x in the figure), the set recording power has an error.

Therefore, the temperature (Tr) of the optical disk 1 is detected from the peripheral temperature of the optical disk 1, and the constant setting means 22 calculates the optimum constant (αt) for each temperature using the equation (3).
Make the settings for

Here, the respective values of Twt and Tc may be recorded in a predetermined area of the optical disc 1, for example, in a lead-in area, or in the optical disc apparatus, for example, the control section 21.
Alternatively, it may be recorded in the constant setting means 22.

The method of setting the optimum constant (αt) for the temperature of the optical disc 1 is not limited to the method obtained from the equation (3). For example, the temperature range and the temperature range as shown in FIG. The setting may be made using a table in which the optimum constants for each temperature range are paired. At this time, the detected ambient temperature Ttest of the optical disc 1 is set to the minimum temperature TminN <Ttest.
<If the maximum temperature TmaxN is satisfied, α is used as a constant.
Set tN. Also in this case, the correspondence table of FIG. 5B may be recorded in a predetermined area of the optical disc 1 or may be recorded in the optical disc device.

Thus, it is possible to set the recording power suitable for the temperature of the optical disc 1. That is, as compared with the case where the minimum recording power is multiplied by a constant value regardless of the temperature, recording at a low temperature is prevented from being performed with a recording power higher than the optimum recording power, thereby reducing the risk of cross writing. Further, at high temperatures, it is possible to prevent recording with a recording power lower than the optimum recording power, thereby enabling highly reliable recording.

If it is considered that the difference between the ambient temperature of the optical disk 1 and the actual temperature of the optical disk 1 is large, for example, immediately after the disk is replaced, there is a possibility that an erroneous constant may be set as αt. It is desirable to set a predetermined value (hereinafter referred to as αt0) as αt or set a constant (α ′) according to a flowchart of FIG. .

The method of detecting the temperature of the optical disk 1 is not limited to the method of detecting the temperature from the peripheral temperature of the optical disk 1, but the temperature of the optical disk 1 may be directly detected using a temperature sensor or the like.

Next, in step 2 (S 2) of FIG. 4A, the constant setting means 22 corrects αt according to the linear velocity of the optical disk 1. Here, the corrected αt is αt ′
And

FIG. 6A shows an example of changes in Pmin and Pcw with respect to the linear velocity of the optical disk 1.

As described above, a desired track on the optical disc 1 is irradiated with the light beam, and the recording film 32 on the optical disc 1 is irradiated.
The data is recorded on the optical disc 1 by raising the temperature of the optical disk 1 to a predetermined temperature, for example, the Curie temperature or higher.

Here, when the linear velocity of the optical disk 1 increases, the energy of the light beam applied to a certain area decreases, so that the laser power required to raise the optical disk 1 to a predetermined temperature increases. As a result, when the linear velocity of the optical disk 1 increases, Pmin increases, and similarly, when the linear velocity decreases, Pmin decreases. For example, when the linear velocity increases by a factor of m, Pmin increases by a factor of ((m) ^1/4 ).

On the other hand, since the cross write is generated due to heat propagation (thermal diffusion) to the adjacent track, Pcw is more affected by the linear velocity of the optical disc 1 than Pmin. For example, when the linear velocity of the optical disc 1 decreases,
Heat is accumulated in the recording film 32, and heat diffusion to adjacent tracks is likely to occur. For this reason, the linear velocity becomes m times larger and Pm
When in becomes ((m) ^1/4 ) times, for example, Pc
w becomes ((m) ^1/3 ) times.

Then, the constant setting means 22 calculates the ratio of the linear velocity of the optical disk 1 (this is m) to the linear velocity of the optical disk 1 (this is m), and the linear velocity is higher than the predetermined linear velocity (m > 1), the constant (αt) is corrected so as to increase, and conversely, the linear velocity is lower than the predetermined linear velocity (m <
In case 1), correction is made so that the constant (αt) becomes smaller.

Here, Pmin and P with respect to the linear velocity
The rate of change of cw (these are n_Pmin and n_Pcw, respectively, where n_Pmin and n_Pmin).
Pcw is a function of m) is a value specific to the optical disc 1 and / or the optical head 3. Therefore, the ratio (m) to the predetermined linear velocity (v0) is calculated from the detected linear velocity, and the value is used to correct αt by the following equation (4) to obtain αt ′.

Αt ′ = αt × (n_Pcw / n_Pmin) (4) For example, n_Pmin = (m) ^1/4 , n_Pcw =
(M) In the case of ^1/3 , if the linear velocity of the optical disc 1 becomes 1.5 times, from the equation (4), αt ′ = αt × ((1.5) ^1/3 /(1.5) ^{1 / 4)} the ≒ 1.03 · αt.

Thus, it is possible to set the recording power suitable for the linear velocity of the optical disk 1. That is, as compared with the case where the minimum recording power is multiplied by a constant value irrespective of the linear velocity, when the linear velocity is high, recording with a recording power lower than the optimum recording power is prevented, thereby enabling highly reliable recording. . Further, when the linear velocity is slow, it is possible to prevent recording with a recording power higher than the optimum recording power, thereby reducing the risk of cross writing.

Here, each function of n_Pmin and n_Pcw or the coefficient of each function may be recorded in a predetermined area of the optical disc 1, for example, a lead-in area, or may be recorded in the optical disc apparatus, for example, the control unit 21 or the constant setting means. 22 may be recorded. Also, n_Pmi
n, not the individual coefficients of n_Pcw, but n_Pcw / n
The coefficient after the calculation of _Pmin may be used.

Similarly, the value of the predetermined linear velocity (v0) is
It may be recorded in a predetermined area of the optical disc 1 or may be recorded in the optical disc device.

Next, in step 3 (S3) of FIG. 4A, the constant setting means 22 corrects αt ′ according to the light beam focusing state. Then, the corrected αt ′ is input to the control unit 21 as a constant (α ′) that is multiplied by the minimum recording power when setting the laser power (optimal recording power) used for data recording.

FIG. 7 shows an example of a change in the condensing state of the light beam. In the case where a radial tilt occurs in which the optical disc 1 is inclined in the radial direction with respect to the optical head 3, changes in Pmin and Pcw with respect to the radial tilt are shown. An example is shown.

Due to defocus, tilt of the disk, etc.,
When the focusing state of the light beam is deteriorated, the equivalent laser power is reduced, so that Pmin is increased. At this time, P
Although the cw also increases, the laser spot of the light beam is deformed due to the deterioration of the focusing state, and thermal diffusion to adjacent tracks is likely to occur. In particular, when radial tilt occurs, heat diffusion to adjacent tracks increases. For this reason,
The change in Pcw due to an increase in radial tilt (deterioration of the light beam focusing state) is smaller than that of Pmin.

For example, radial tilt (tilt amount = R
When Tmin changes with respect to T) as Pmin = c_Pmin.RT ² + Pmin0 (5), Pcw changes, for example, as in the following equation (6).

Pcw = c_Pcw · RT ² + Pcw0 (6) (however, c_Pcw <c_Pmin) Here, Pmin0 and Pcw0 are the optical disk at a predetermined temperature (this is Tr0) and a predetermined linear velocity (v0).
And Pmin and Pcw when the light beam is well focused. Also, c_Pmin and c_Pc
w is the rate of change of Pmin and Pcw with respect to the light collection state.

For this reason, the condensing state of the light beam is detected from the detected Pmin by the constant setting means 22, and when the condensing state is poor, correction is made so that the constant (αt ′) becomes large.

For example, if it is known in advance that the main cause of the deterioration of the focusing state is a radial tilt, the detection of the focusing state of the light beam is determined by the Pmin detected by the minimum recording power detecting means 8. It can be performed using Pmin when the light-collecting state is good (this is referred to as Pmin0 ″).

Pmin0 ″ is determined by Pm according to the detected value of the ambient temperature and the linear velocity of the optical disk 1 at the time of detecting Pmin.
It can be calculated by correcting in0.

First, Pmin0 is corrected to Pmin0 ′ according to the ambient temperature (Tr) of the optical disk 1 using the equation (1).

Pmin0 ′ = k (Tc−Tr) = Pmin0 · (Tc−Tr0) / (Tc−Tr) Further, according to the ratio (m) to a predetermined linear velocity (v0),
Pmin0 ′ is corrected to Pmin0 ″.

Pmin0 ″ = (m) ^1/4 · Pmin0 ′ = (m) ^1/4 · Pmin0 · (Tc−Tr0) / (Tc−Tr) Pmin0 ″ calculated in this way is expressed by the following equation (5). Pm
By substituting into in0, the tilt amount = RT can be calculated.

At this time, αt ′ is corrected according to the equation (7) to obtain α ′.

Α ′ = αt ′ × {(c_Pcw · RT ² + Pcw0) / Pcw0} / {(c_Pmin · RT ² + Pmin0) / Pmin0} (7) For example, c_Pmin = 0.09, c_Pcw = 0.
003, Pmin0 = 6 mW, Pcw = 9 mW,
If RT = 10 mrad, α ′ =
0.90 · αt ′.

As a result, it is possible to set the recording power suitable for the light beam focusing state. In other words, compared to multiplying the minimum recording power by a fixed value regardless of the light beam condensing state, when the light condensing state is poor, it is possible to prevent recording with a recording power higher than the optimum recording power, thereby reducing the risk of cross writing. Performance can be reduced.

The method of detecting the condensing state of the light beam is not limited to the method of detecting the light beam from Pmin, but may be provided by separately providing a tilt amount detecting means or the like.

Even when the main cause of the deterioration of the light-collecting state is not known, αt ′ may be corrected according to Pmin. For example, the correction is performed by the following equation (8).

Α ′ = αt ′ × (Pmin0 ″ / Pmin) (8) Since Pmin increases as the focusing state deteriorates, α ′ decreases according to equation (8), which is also optimal. It is possible to prevent recording with a recording power higher than the recording power and reduce the risk of cross writing.

Here, c_Pmin, Pmin0, c_
Each value of Pcw and Pcw0 may be recorded in a predetermined area of the optical disc 1, for example, a lead-in area, or may be recorded in the optical disc apparatus, for example, in the control unit 21 or the constant setting unit 22.

Similarly, the value of the predetermined temperature (Tr0) is
It may be recorded in a predetermined area of the optical disc 1 or may be recorded in the optical disc device.

The control unit 21 controls the minimum recording power detecting means 8
The power (α ′ · Pmin) obtained by multiplying the Pmin detected in (1) by the constant (α ′) set by the constant setting means 22 is set as the optimum recording power to the laser power used for data recording.

Thus, when setting the laser power (optimum recording power) to be used for data recording, the constant to be multiplied by the minimum recording power is set to an optimum value in accordance with recording conditions such as the light beam condensing state. Can be set. Then, by setting the laser power used for data recording using this value, cross writing can be prevented and highly reliable recording can be performed.

FIG. 4A shows an example in which the constant (α ′) by which the minimum recording power is multiplied is changed according to the light beam condensing state, the linear velocity of the optical disk 1 and the temperature of the optical disk 1. However, using all detected values, α '
Need not be set, one of them may be set, or any combination may be used. That is, the setting or correction may be performed by any one of S1 to S3 in FIG. 4A, or the setting or correction may be performed by an arbitrary combination of S1 to S3. In FIG. 4A,
When the setting (S1) according to the temperature is not performed, a predetermined value (αt0) is set as αt.

When the correction (S1) according to the ambient temperature in FIG. 4A is not performed, the constant (α ′) may be set according to the flowchart shown in FIG. 4B.

FIG. 4B is a second example of a flowchart showing the recording power control method of the present invention.

First, step 1 (S) shown in FIG.
In 1), the constant setting means 22 sets an optimum constant (αv) according to the linear velocity of the optical disc 1.

Here, as a method of setting an optimum constant (αv) for the linear velocity of the optical disk 1, for example, FIG.
As shown in (1), the linear velocity range and the constants optimal for each linear velocity range are set using a table. For example, the detected linear velocity Vtest is the minimum linear velocity VminN <Vtest
<If the maximum linear velocity VmaxN is satisfied, αvN is set as a constant.

Next, step 2 (S) shown in FIG.
In 2), the constant setting unit 22 corrects αv according to the light beam condensing state, and sets the minimum recording power when setting the corrected αv to the laser power (optimum recording power) used for data recording. Is input to the control unit 21 as a constant (α ′) multiplied by.

The correction of the constant according to the light beam condensing state is the same as in S3 of FIG. 4A, and a description thereof will be omitted.

Note that the correspondence table of FIG.
May be recorded in a predetermined area, for example, a lead-in area, or may be recorded in the optical disk device, for example, in the control unit 21 or the constant setting unit 22.

FIG. 4B shows an example in which the constant (α ′) by which the minimum recording power is multiplied is made variable in accordance with the light beam condensing state and the linear velocity of the optical disk 1. It is not necessary to set α 'using the detection value of
The setting may be made using any one of the detection values. That is, the correction may be made by using one of S1 and S2 in FIG. In FIG. 4B, when the setting (S1) according to the linear velocity is not performed, a predetermined value (αv0) is set as αv.

(Second Embodiment) FIG. 8 is a block diagram showing the configuration of an optical disk device according to a second embodiment of the present invention. Note that, in FIG. 8, components denoted by the same reference numerals as those in FIG. 1 indicate the same components, and a description thereof will be omitted.

In FIG. 8, reference numeral 41 denotes a constant setting means for setting a constant value by which the minimum recording power is multiplied when setting the optimum recording power. Reference numeral 42 denotes an intermittent light beam which is intermittently irradiated at the time of recording. It is an intermittent rate detecting means for detecting the rate. A control unit 43 controls the spindle motor 2, the optical head 3, the laser power control unit 4, and the magnetic head 5, and sets an optimum recording power.

The minimum recording power detecting means 8
The optimum recording power setting means 44
Is configured.

Next, the operation of the optical disk device of the second embodiment configured as described above will be described.

As in the optical disk device of the first embodiment,
Pmin is detected by the minimum recording power detection means 8, and the detection result of Pmin is input to the constant setting means 41 and the control unit 43.

The intermittent rate detecting means 42 detects the intermittent rate of the light beam intermittently irradiated, and the result of the detection is input to the constant setting means 22. The intermittent rate is recorded, for example, in the constant setting unit 41 or the control unit 43 in the optical disc device.

The constant setting means 41 sets a constant value to be multiplied by the minimum recording power when setting the optimum recording power in accordance with the intermittent rate of the light beam, and inputs the set value (α ') to the control unit 43. Is done.

A recording method of intermittently irradiating a light beam at the time of recording has been proposed in order to reduce the power consumption of the optical head 3 and to suppress the fluctuation of the position of a recording mark formed on the optical disk 1.

FIG. 9A shows an example of the change of Pmin and Pcw with respect to the intermittent rate of the light beam.
Note that the intermittent rate of the light beam is, as shown in FIG.
It is the ratio of the time (Toff) during which the laser light is not irradiated to the pulse period (T). The vertical axis in FIG. 9A is the peak value (recording power) of the light beam irradiated in a pulsed manner.

Here, when the intermittent rate of the light beam increases, the time during which the laser beam is not irradiated becomes longer, so that
The energy of the light beam applied to a certain area decreases. Therefore, the laser power required to raise the optical disk 1 to a predetermined temperature increases, and Pmin increases.

On the other hand, since the cross write is generated due to the propagation of heat (thermal diffusion) to the adjacent track, Pcw is more affected by the intermittent rate of the light beam than Pmin. For example, when the intermittent rate of the light beam decreases, heat is accumulated in the recording film 32, and heat diffusion to adjacent tracks is likely to occur.

For this reason, the constant setting means 41 compares the predetermined intermittent rate (referred to as g0) with the intermittent rate of the light beam. Conversely, when the intermittent rate is smaller than the predetermined intermittent rate, correction is made so that the constant becomes smaller. For example, the correction is performed by the following equation (9).

Α ′ = α0 × (detection result of intermittent rate / g0) (9) Here, α0 is used for data recording at a predetermined temperature, a predetermined linear velocity, a predetermined light-collecting state, and a predetermined intermittent rate. A laser power (optimum recording power) is set as a constant to be multiplied by Pmin.

As the intermittent rate of the light beam becomes smaller, α ′ becomes smaller according to the equation (9), so that recording with a recording power higher than the optimum recording power can be prevented, and the danger of cross writing can be reduced.

The values of α0 and g0 are recorded in a predetermined area of the optical disc 1, for example, a lead-in area.

Thus, when setting the laser power (optimum recording power) used for data recording, it is possible to set a constant for multiplying the minimum recording power to an optimum value according to the intermittent rate of the light beam. Become.

(Third Embodiment) FIG. 10 shows a third embodiment of the present invention.
FIG. 1 is a block diagram illustrating a configuration of an optical disc device according to an embodiment. Note that, in FIG. 10, the components denoted by the same reference numerals as those in FIG. 1 or FIG. 8 indicate the same components, and description thereof will be omitted.

In FIG. 10, reference numeral 51 denotes a signal processing unit for performing predetermined processing on a reproduction signal; 52, a clock generation unit for generating a clock used for recording and / or reproduction of a signal;
An address demodulator 3 demodulates an address. 54
Is a detector (correlation detecting means) for detecting a correlation between a known recording pattern and a reproduction signal obtained when reproducing the recording pattern, and 55 is a minimum recording power (for forming a recording mark of a reproduction limit on the optical disc 1). Pmin) is a minimum recording power detection means for detecting the minimum recording power. A control unit 56 controls the spindle motor 2, the optical head 3, the laser power control means 4, and the magnetic head 5, and sets an optimum recording power.

The minimum recording power detecting means 5
5 and the control unit 56, the optimum recording power setting means 5
7 is configured.

Next, the operation of the optical disk device configured as described above will be described below.

The optical head 3 irradiates the optical disk 1 with a light beam based on the information from the control unit 56, detects the reflected light, and converts it into an electric signal. This detection signal is sent to a signal processing unit 51, a clock generation unit 52, an address demodulator 5
3, and a focus control unit and a tracking control unit (not shown).

A reproduction signal corresponding to the recorded information recorded on the optical disc 1 is supplied to the signal processing section 51, and the signal processing section 51 performs processing such as noise removal.

The clock generation section 52 extracts clock generation information from the signal supplied from the optical head 3 and generates a clock used for recording and reproducing the signal. This clock is supplied to the detector 54 and the control unit 56.

For example, in an optical disk of the sample servo system, clock pits, which are clock generation information, are recorded (preformatted) in advance over the entire circumference, and this information is detected from a signal supplied from the optical head 3. For example, by dividing the frequency by using a PLL, a clock used for recording and reproduction can be generated. Of course, the clock generation information does not need to be recorded in pits, and may be with or without grooves.
A groove (groove) meandering (wobbling) at a predetermined frequency may be used. Further, the present invention is not limited to the sample servo type optical disk, but may be any optical disk device that uses substantially the same clock for recording and reproduction.

The address demodulator 53 extracts address information from a signal supplied from the optical head 3, demodulates an address based on the information, and knows on which position on the optical disk 1 the light beam is irradiated. To detect the address. The detected address is supplied to the detector 54 and the control unit 56.

Next, the operation of the detector 54 and the optimum recording power setting means 57 will be described with reference to the timing chart of FIG. FIG. 11 shows a clock generation unit 52.
, A recording pattern synchronized with the clock, a recording power, a reproduced signal output from the signal processing unit 51, and a detector output output from the detector 54.

First, the laser power control means 4 sets a power (for example, P0) sufficiently lower than the power for actually recording data based on the information from the control unit 56. The optical head 3 and the magnetic head 5 write a recording pattern synchronized with a clock as shown in FIG.
Is recorded on the optical disc 1 with the power set by

At this time, based on the information from the control unit 56, the laser power control means 4 changes the recording power stepwise over a predetermined number of steps with P0 as an initial value, as shown in FIG. Settings are made (the recording power in each stage is P0, P1, P2,...).

The recording pattern is also supplied to the detector 54.

Although the recording power is shown in FIG. 11 as increasing monotonically, the present invention is not limited to this, and the recording power may be monotonously decreased, or the power may be set so as to increase and decrease repeatedly. .

When this recording pattern is reproduced by the optical head 3 and input to the signal processing unit 51, a low-frequency noise is removed by the signal processing unit 51, and then a reproduction signal as shown in FIG. 11 is output. The signal is input to the detector 54. When the detection of Pmin is performed in a recorded area in the data recording area 33, the reproduced signal includes the optical disc 1
In addition to the noise component caused by the optical head 3 and the noise component, the signal component of data previously recorded in the area is included.

In the Pmin detection method shown in the first and second embodiments, since the intensity of the reproduction signal is used for the detection of Pmin, the detection of Pmin is performed in an area where it is clear that the Pmin has been erased in advance, for example, the optical disk 1. In order to perform this in a lead-in area (not shown) in the middle or in the data recording area 33, it is necessary to previously erase data previously recorded in the area. On the other hand, the third embodiment is characterized in that, even when Pmin is detected in the data recording area 33, there is no need to previously erase data previously recorded in the area.

In the detector 54, the correlation between the recording pattern and the reproduced signal is detected. This is nothing more than the detection of the autocorrelation, whereby it is possible to know how accurately the recording pattern recorded at each recording power is recorded. The detected result is input to the minimum recording power detecting means 55 as a correlation value.

Here, since substantially the same clock is used for recording and reproduction of a signal, for example, in FIG. 11, the period in which the recording pattern is logic "H" is "1", and the period in which the logic pattern is logic "L" is By taking the product of the recording pattern and the reproduction signal as "-1" and integrating for a predetermined period, signal components having no correlation with the recording pattern, such as noise components and previously recorded data, are canceled out. . For this reason, even if the signal is very small, the signal component of the recording pattern recorded on the optical disc 1 can be detected, and the detector 54 detects this as a correlation value.

The correlation value is, for example, divided by the integration period (t0, t1, t2...) Of the integration result of each stage recorded with the same power as in the detector output shown in FIG. It can be obtained by: Here, the correlation values detected at each stage are denoted by C0, C1, C2,. In an area where the recording power is low and recording is not performed, the correlation value is almost 0 (zero).

It should be noted that the integration period (t
(0, t1, t2,...) Are known to be the same, the integration result may be directly used as the correlation value without being divided according to the integration period.

Further, the detector 45 may detect the correlation by setting the period in which the recording pattern is logic "H" to "-1" and the period in which the recording pattern is logic "L" to "1".

The minimum recording power detecting means 55 compares the correlation value with a predetermined level, and detects that the magnitude relation has changed. Then, the recording power for recording this recording pattern from the address at this time (for example, P
2) is detected, and this is defined as Pmin. The detection result of Pmin is input to the constant setting unit 22 and the control unit 56.

In the constant setting means 22, Pmin and / or
Alternatively, according to the linear velocity of the optical disk 1 and / or the ambient temperature of the optical disk 1, a constant value by which the minimum recording power is multiplied when setting the optimum recording power is set, and the set value (α ′) is set by the control unit 56. Is input to

The method for setting α ′ is the same as in the first or second embodiment, and a description thereof will not be repeated.

The control unit 56 includes a minimum recording power detection unit 5
The power (α ′ · Pmin) obtained by multiplying Pmin detected in step 5 by a constant set by the constant setting means 22 is set as the optimum recording power to the laser power used for data recording.

As a result, even when the minimum recording power for the optical disc 1 is detected in an area where data is actually recorded, it is not necessary to previously erase data previously recorded in the area, and Pmin can be reduced. Detection can be performed with high accuracy and in a short time. In addition, since Pmin can be detected in the area immediately before recording, even when the optical disc 1 is tilted or warped, or has a temporal change such as defocus or temperature, an optimum recording power is always set. It becomes possible. Further, since it is possible to detect a minute signal component, the detection of Pmin is
Since the recording can be performed using a power sufficiently lower than the power for recording data in the vicinity of min, Pmi
There is no danger of cross-write when n is detected.

The reproduced signal may be input to the detector 54 after being digitized by an A / D converter (not shown). In this case, similarly, in the detector 54, the period in which the recording pattern is logic "H" is "1", the period in which the recording pattern is logic "L" is "-1", or the period in which the logic pattern is "H" is " Assuming that a period of -1 "and logic" L "is" 1 ", the recording pattern is multiplied by the digitized reproduction signal, and the multiplied value is set for a predetermined period (for example, t0, t1,.
t2,...), the correlation can be detected.

[0148]

As described above, according to the optical disk apparatus and the recording power control method of the present invention, when setting the laser power (optimum recording power) used for recording data, the constant by which the minimum recording power is multiplied is set. An optimum value can be set according to recording conditions such as the light beam condensing state.

Further, even when the light beam is intermittently irradiated at the time of recording, it is possible to set a constant for multiplying the minimum recording power to an optimum value according to the intermittent rate.

Also, by using the correlation detection to detect the minimum recording power, even when the minimum recording power is to be performed in the data recording area, it is not necessary to previously erase the data previously recorded in the data recording area. This makes it possible to detect the recording power with high accuracy and in a short time, which is extremely effective in practice.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an optical disk device according to a first embodiment of the present invention.

FIG. 2 is a perspective view showing a configuration of an optical disc according to a first embodiment, a second embodiment, and a third embodiment of the present invention.

FIG. 3 is a relationship diagram showing a relationship between a reproduction signal intensity and a recording power.

FIGS. 4A and 4B are flowcharts showing a recording power control method according to the first embodiment of the present invention.

FIG. 5A is a relationship diagram showing a relationship between a ratio of a minimum recording power to an optimum recording power and a disk temperature;
(B) is a correspondence table between disk temperature ranges and constants that are optimal for each temperature range.

FIG. 6A is a relationship diagram showing a relationship between a recording power and a linear velocity, and FIG. 6B is a correspondence table between a linear velocity range and a constant optimal for each linear velocity range.

FIG. 7 is a relationship diagram showing a relationship between a recording power and a focusing state.

FIG. 8 is a block diagram illustrating a configuration of an optical disc device according to a second embodiment of the present invention.

FIG. 9A is a relationship diagram showing a relationship between recording power and an intermittent rate, and FIG. 9B is an explanatory diagram for explaining the intermittent rate.

FIG. 10 is a block diagram showing a configuration of an optical disc device according to a third embodiment of the present invention.

11 is a signal waveform diagram of each part of the optical disk device shown in FIG.

FIG. 12 is a block diagram illustrating a configuration of a conventional optical disc device.

FIG. 13 is a relationship diagram showing a relationship between a reproduction signal intensity and a recording power.

FIGS. 14A and 14B are relationship diagrams showing the relationship between the reproduction signal intensity and the recording power when the light-collecting state changes.

FIG. 15 is a relationship diagram showing a relationship between a cross write amount and a recording power when a track pitch changes.

FIG. 16 is a relationship diagram showing a relationship between a cross write amount and a recording power when a light condensing state changes.

[Explanation of symbols]

 Reference Signs List 1 optical disk 2 spindle motor 3 optical head (reproducing means, recording means) 4 laser power control means 5 magnetic head (recording means) 6 bandpass filter 7 detector 8, 55 minimum recording power detecting means 9, 21, 43, 56 control Parts 22, 41 constant setting means 23 linear velocity detecting means 24 temperature detecting means 25, 44, 57 optimum recording power setting means 54 detector (correlation detecting means)

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Takashi Inoue 1006 Kazuma Kadoma, Osaka Prefecture F-term (reference) in Matsushita Electric Industrial Co., Ltd. AA23 BA01 BB02 BB03 DA01 DA14 EC09 FA02 HA19 HA57

Claims (10)

[Claims] 1. An optical disk apparatus for recording and reproducing data by irradiating an optical disk with a light beam, comprising: a recording unit for recording information on the optical disk; and a light beam for irradiating the optical disk with respect to the recording unit. Laser power control means for controlling the power of the optical disc; reproducing means for reproducing the information recorded on the optical disc; detecting a minimum recording power for forming a recording mark of a reproducible limit on the optical disc; An optical disc device comprising: an optimum recording power setting unit that sets a power obtained by multiplying a constant by a constant as an optimum recording power; and a constant setting unit that sets a value of the constant. 2. The optical disk device according to claim 1, wherein the constant setting unit sets the value of the constant according to a temperature of the optical disk. 3. The optical disk device according to claim 1, wherein the constant setting unit sets the value of the constant according to a linear velocity of the optical disk. 4. The optical disk device according to claim 1, wherein the constant setting unit sets the value of the constant according to a focusing state of the light beam. 5. The optical disc apparatus according to claim 4, wherein the condensing state of the light beam is obtained from a minimum recording power for forming the recording mark of the reproduction limit. 6. The optical disc device according to claim 1, wherein the optical disc device records data by intermittently irradiating a light beam, wherein the constant setting means sets the value of the constant according to the intermittent rate of the light beam. The optical disk device according to claim 1, wherein the setting is performed. 7. A correlation detecting means for detecting a correlation between a recording pattern to be recorded on the optical disk by the recording means and a reproduction signal obtained when the recording pattern is reproduced by the reproducing means, The recording power setting means compares the output of the correlation detection means obtained when the laser power is stepwise changed by the laser power control means with a predetermined level, and determines the recording power when the magnitude relation is changed. 2. The method according to claim 1, wherein the minimum recording power is detected.
An optical disk device as described in the above. 8. A recording power control method for an optical disk device for recording data by irradiating an optical disk with a light beam, comprising: detecting a minimum recording power for forming a recording mark of a reproduction limit on the optical disk; A recording power control method for an optical disk device, wherein a power obtained by multiplying a power by a constant is set as an optimum recording power, and the value of the constant is changed according to a recording condition. 9. The apparatus according to claim 8, wherein the value of the constant is set according to at least one of a temperature of the optical disk, a linear velocity of the optical disk, and a state of condensing the light beam. Recording power control method for an optical disk device. 10. The recording power control method for an optical disk device according to claim 9, wherein the condensing state of the light beam is determined from a minimum recording power for forming a recording mark of a reproduction limit on the optical disk.